diff --git a/ChangeLog b/ChangeLog
index 39bcd6f2c6..4790aa85fe 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -346,7 +346,7 @@ Version 7.1.0 - 25 September 2019
  - Upgrade Symfony and dependencies to version 4.3.
  - Use Doctrine for migrations and initial data.
  - Add option (enabled by default) to limit files passed to
-   language compilers by langauge extension list.
+   language compilers by language extension list.
  - Add option to add a whole team category to a contest.
  - Allow admin to specify print command using configuration setting.
  - Show metadata for judging runs.
diff --git a/judge/judgedaemon.main.php b/judge/judgedaemon.main.php
index 2953e8a781..9448713a18 100644
--- a/judge/judgedaemon.main.php
+++ b/judge/judgedaemon.main.php
@@ -624,7 +624,7 @@ private function checkDiskSpace(string $workdirpath): void
 
     private function judgingDirectory(string $workdirpath, array $judgeTask): string
     {
-        if (filter_var($judgeTask['submitid'], FILTER_VALIDATE_INT) === false ||
+        if (filter_var($judgeTask['submitid'], FILTER_VALIDATE_REGEXP, ['options' => ['regexp' => '/^[a-zA-Z0-9_.-]+$/']]) === false ||
             filter_var($judgeTask['jobid'], FILTER_VALIDATE_INT) === false) {
             error("Malformed data returned in judgeTask IDs: " . var_export($judgeTask, true));
         }
@@ -1289,7 +1289,7 @@ private function compile(
 
             // Revoke readablity for domjudge-run user to this workdir.
             chmod($workdir, 0700);
-            logmsg(LOG_NOTICE, "Judging s$judgeTask[submitid], task $judgeTask[judgetaskid]: compile error");
+            logmsg(LOG_NOTICE, "Judging $judgeTask[submitid], task $judgeTask[judgetaskid]: compile error");
             return false;
         }
 
@@ -1353,7 +1353,7 @@ private function compile(
         // What does the exitcode mean?
         if (!isset($this->EXITCODES[$retval])) {
             alert('error');
-            $description = "Unknown exitcode from compile.sh for s$judgeTask[submitid]: $retval";
+            $description = "Unknown exitcode from compile.sh for $judgeTask[submitid]: $retval";
             logmsg(LOG_ERR, $description);
             $this->disable('compile_script', 'compile_script_id', $judgeTask['compile_script_id'], $description, $judgeTask['judgetaskid'], $compile_output);
 
@@ -1568,7 +1568,7 @@ private function runTestcase(
             // What does the exitcode mean?
             if (!isset($this->EXITCODES[$retval])) {
                 alert('error');
-                error("Unknown exitcode ($retval) from testcase_run.sh for s$judgeTask[submitid]");
+                error("Unknown exitcode ($retval) from testcase_run.sh for $judgeTask[submitid]");
             }
             $result = $this->EXITCODES[$retval];
 
diff --git a/webapp/migrations/Version20251024122021.php b/webapp/migrations/Version20251024122021.php
new file mode 100644
index 0000000000..fbb5a116a3
--- /dev/null
+++ b/webapp/migrations/Version20251024122021.php
@@ -0,0 +1,141 @@
+<?php
+
+declare(strict_types=1);
+
+namespace DoctrineMigrations;
+
+use Doctrine\DBAL\Schema\Schema;
+use Doctrine\Migrations\AbstractMigration;
+
+/**
+ * Auto-generated Migration: Please modify to your needs!
+ */
+final class Version20251024122021 extends AbstractMigration
+{
+    public function getDescription(): string
+    {
+        return 'Change language ID to be an auto increment integer';
+    }
+
+    public function up(Schema $schema): void
+    {
+        // We need to do some juggling to get this to work:
+        // - First we drop the foreign keys from tables referencing langid. We also drop compound
+        // - Then we add a temporary integer langid column to all these tables, since we can't
+        //   change the langid column itself, because MySQL will try to convert the strings to
+        //   integers and fail. We set the langid column in the language table to auto increment,
+        //   so it's filled by MySQL.
+        // - Now we copy the langid_int values to other tables.
+        // - Then we drop the old langid columns and drop any (compound) primary keys that use it.
+        // - Next, we rename the langid_int columns back to langid.
+        // - Finally we add back all primary and foreign keys.
+
+        $this->addSql('ALTER TABLE submission DROP FOREIGN KEY submission_ibfk_4');
+        $this->addSql('ALTER TABLE problemlanguage DROP FOREIGN KEY FK_46B150BB2271845');
+        $this->addSql('ALTER TABLE version DROP FOREIGN KEY FK_BF1CD3C32271845');
+        $this->addSql('ALTER TABLE contestlanguage DROP FOREIGN KEY FK_ADCB43232271845');
+
+        $this->addSql('ALTER TABLE language ADD langid_int INT UNSIGNED AUTO_INCREMENT UNIQUE AFTER langid');
+        $this->addSql('ALTER TABLE contestlanguage ADD langid_int INT UNSIGNED NOT NULL AFTER langid');
+        $this->addSql('ALTER TABLE problemlanguage ADD langid_int INT UNSIGNED NOT NULL AFTER langid');
+        $this->addSql('ALTER TABLE submission ADD langid_int INT UNSIGNED DEFAULT NULL AFTER langid');
+        $this->addSql('ALTER TABLE version ADD langid_int INT UNSIGNED DEFAULT NULL AFTER langid');
+
+        $this->addSql('UPDATE contestlanguage c JOIN language l ON c.langid = l.langid SET c.langid_int = l.langid_int');
+        $this->addSql('UPDATE problemlanguage p JOIN language l ON p.langid = l.langid SET p.langid_int = l.langid_int');
+        $this->addSql('UPDATE submission s JOIN language l ON s.langid = l.langid SET s.langid_int = l.langid_int WHERE s.langid IS NOT NULL');
+        $this->addSql('UPDATE version v JOIN language l ON v.langid = l.langid SET v.langid_int = l.langid_int WHERE v.langid IS NOT NULL');
+        $this->addSql('UPDATE auditlog a JOIN language l ON a.dataid = l.langid AND a.datatype = "language" SET a.dataid = l.langid_int WHERE a.dataid IS NOT NULL');
+
+        $this->addSql('ALTER TABLE language DROP PRIMARY KEY');
+        $this->addSql('ALTER TABLE language DROP COLUMN langid');
+        $this->addSql('ALTER TABLE contestlanguage DROP PRIMARY KEY');
+        $this->addSql('ALTER TABLE contestlanguage DROP COLUMN langid');
+        $this->addSql('ALTER TABLE problemlanguage DROP PRIMARY KEY');
+        $this->addSql('ALTER TABLE problemlanguage DROP COLUMN langid');
+        $this->addSql('ALTER TABLE submission DROP COLUMN langid');
+        $this->addSql('ALTER TABLE version DROP COLUMN langid');
+
+        $this->addSql('ALTER TABLE language CHANGE langid_int langid INT UNSIGNED AUTO_INCREMENT NOT NULL COMMENT \'Language ID\'');
+        $this->addSql('ALTER TABLE contestlanguage CHANGE langid_int langid INT UNSIGNED NOT NULL COMMENT \'Language ID\'');
+        $this->addSql('ALTER TABLE problemlanguage CHANGE langid_int langid INT UNSIGNED NOT NULL COMMENT \'Language ID\'');
+        $this->addSql('ALTER TABLE submission CHANGE langid_int langid INT UNSIGNED DEFAULT NULL COMMENT \'Language ID\'');
+        $this->addSql('ALTER TABLE version CHANGE langid_int langid INT UNSIGNED DEFAULT NULL COMMENT \'Language ID\'');
+
+        $this->addSql('ALTER TABLE language ADD PRIMARY KEY (langid), DROP INDEX langid_int');
+        $this->addSql('ALTER TABLE contestlanguage ADD PRIMARY KEY (cid, langid)');
+        $this->addSql('ALTER TABLE problemlanguage ADD PRIMARY KEY (probid, langid)');
+
+        $this->addSql('ALTER TABLE submission ADD INDEX langid (langid), ADD CONSTRAINT submission_ibfk_4 FOREIGN KEY (langid) REFERENCES language (langid) ON DELETE CASCADE');
+        $this->addSql('ALTER TABLE problemlanguage ADD INDEX IDX_46B150BB2271845 (langid), ADD CONSTRAINT FK_46B150BB2271845 FOREIGN KEY (langid) REFERENCES language (langid) ON DELETE CASCADE');
+        $this->addSql('ALTER TABLE version ADD INDEX IDX_BF1CD3C32271845 (langid), ADD CONSTRAINT FK_BF1CD3C32271845 FOREIGN KEY (langid) REFERENCES language (langid) ON DELETE CASCADE');
+        $this->addSql('ALTER TABLE contestlanguage ADD INDEX IDX_ADCB43232271845 (langid), ADD CONSTRAINT FK_ADCB43232271845 FOREIGN KEY (langid) REFERENCES language (langid) ON DELETE CASCADE');
+    }
+
+    public function down(Schema $schema): void
+    {
+        // When migrating back, we do the logic in reverse but we have custom logic for setting
+        // the string langid. We set it to the external ID except for a set of 10 known languages
+        // where the external ID differs from our previously used langid.
+
+        $this->addSql('ALTER TABLE submission DROP FOREIGN KEY submission_ibfk_4');
+        $this->addSql('ALTER TABLE problemlanguage DROP FOREIGN KEY FK_46B150BB2271845');
+        $this->addSql('ALTER TABLE version DROP FOREIGN KEY FK_BF1CD3C32271845');
+        $this->addSql('ALTER TABLE contestlanguage DROP FOREIGN KEY FK_ADCB43232271845');
+
+        $this->addSql('ALTER TABLE language ADD langid_str VARCHAR(32) NOT NULL AFTER langid');
+        $this->addSql('ALTER TABLE contestlanguage ADD langid_str VARCHAR(32) NOT NULL AFTER langid');
+        $this->addSql('ALTER TABLE problemlanguage ADD langid_str VARCHAR(32) NOT NULL AFTER langid');
+        $this->addSql('ALTER TABLE submission ADD langid_str VARCHAR(32) DEFAULT NULL AFTER langid');
+        $this->addSql('ALTER TABLE version ADD langid_str VARCHAR(32) DEFAULT NULL AFTER langid');
+
+        $this->addSql("UPDATE language SET langid_str = CASE externalid
+            WHEN 'ada' THEN 'adb'
+            WHEN 'haskell' THEN 'hs'
+            WHEN 'javascript' THEN 'js'
+            WHEN 'kotlin' THEN 'kt'
+            WHEN 'pascal' THEN 'pas'
+            WHEN 'prolog' THEN 'plg'
+            WHEN 'python3' THEN 'py3'
+            WHEN 'python2' THEN 'py2'
+            WHEN 'ruby' THEN 'rb'
+            WHEN 'rust' THEN 'rs'
+            ELSE externalid
+        END");
+
+        $this->addSql('UPDATE contestlanguage c JOIN language l ON c.langid = l.langid SET c.langid_str = l.langid_str');
+        $this->addSql('UPDATE problemlanguage p JOIN language l ON p.langid = l.langid SET p.langid_str = l.langid_str');
+        $this->addSql('UPDATE submission s JOIN language l ON s.langid = l.langid SET s.langid_str = l.langid_str WHERE s.langid IS NOT NULL');
+        $this->addSql('UPDATE version v JOIN language l ON v.langid = l.langid SET v.langid_str = l.langid_str WHERE v.langid IS NOT NULL');
+        $this->addSql('UPDATE auditlog a JOIN language l ON a.dataid = l.langid AND a.datatype = "language" SET a.dataid = l.langid_str WHERE a.dataid IS NOT NULL');
+
+        $this->addSql('ALTER TABLE language DROP PRIMARY KEY');
+        $this->addSql('ALTER TABLE language DROP COLUMN langid');
+        $this->addSql('ALTER TABLE contestlanguage DROP PRIMARY KEY');
+        $this->addSql('ALTER TABLE contestlanguage DROP COLUMN langid');
+        $this->addSql('ALTER TABLE problemlanguage DROP PRIMARY KEY');
+        $this->addSql('ALTER TABLE problemlanguage DROP COLUMN langid');
+        $this->addSql('ALTER TABLE submission DROP COLUMN langid');
+        $this->addSql('ALTER TABLE version DROP COLUMN langid');
+
+        $this->addSql('ALTER TABLE language CHANGE langid_str langid VARCHAR(32) NOT NULL COMMENT \'Language ID\'');
+        $this->addSql('ALTER TABLE contestlanguage CHANGE langid_str langid VARCHAR(32) NOT NULL COMMENT \'Language ID\'');
+        $this->addSql('ALTER TABLE problemlanguage CHANGE langid_str langid VARCHAR(32) NOT NULL COMMENT \'Language ID\'');
+        $this->addSql('ALTER TABLE submission CHANGE langid_str langid VARCHAR(32) DEFAULT NULL COMMENT \'Language ID\'');
+        $this->addSql('ALTER TABLE version CHANGE langid_str langid VARCHAR(32) DEFAULT NULL COMMENT \'Language ID\'');
+
+        $this->addSql('ALTER TABLE language ADD PRIMARY KEY (langid)');
+        $this->addSql('ALTER TABLE contestlanguage ADD PRIMARY KEY (cid, langid)');
+        $this->addSql('ALTER TABLE problemlanguage ADD PRIMARY KEY (probid, langid)');
+
+        $this->addSql('ALTER TABLE submission ADD INDEX langid (langid), ADD CONSTRAINT submission_ibfk_4 FOREIGN KEY (langid) REFERENCES language (langid) ON DELETE CASCADE');
+        $this->addSql('ALTER TABLE problemlanguage ADD INDEX IDX_46B150BB2271845 (langid), ADD CONSTRAINT FK_46B150BB2271845 FOREIGN KEY (langid) REFERENCES language (langid) ON DELETE CASCADE');
+        $this->addSql('ALTER TABLE version ADD INDEX IDX_BF1CD3C32271845 (langid), ADD CONSTRAINT FK_BF1CD3C32271845 FOREIGN KEY (langid) REFERENCES language (langid) ON DELETE CASCADE');
+        $this->addSql('ALTER TABLE contestlanguage ADD INDEX IDX_ADCB43232271845 (langid), ADD CONSTRAINT FK_ADCB43232271845 FOREIGN KEY (langid) REFERENCES language (langid) ON DELETE CASCADE');
+    }
+
+    public function isTransactional(): bool
+    {
+        return false;
+    }
+}
diff --git a/webapp/migrations/Version20251026092516.php b/webapp/migrations/Version20251026092516.php
new file mode 100644
index 0000000000..c0a838e108
--- /dev/null
+++ b/webapp/migrations/Version20251026092516.php
@@ -0,0 +1,66 @@
+<?php
+
+declare(strict_types=1);
+
+namespace DoctrineMigrations;
+
+use Doctrine\DBAL\Schema\Schema;
+use Doctrine\Migrations\AbstractMigration;
+use phpDocumentor\Reflection\Types\Static_;
+
+final class Version20251026092516 extends AbstractMigration
+{
+    protected const ENTITIES = [
+        'clarification' => 'clarid',
+        'contest' => 'cid',
+        'language' => 'langid',
+        'problem' => 'probid',
+        'submission' => 'submitid',
+        'team' => 'teamid',
+        'team_affiliation' => 'affilid',
+        'team_category' => 'categoryid',
+        'user' => ['userid', 'username'],
+    ];
+
+    public function getDescription(): string
+    {
+        return 'Make auditlog IDs reference external IDs';
+    }
+
+    public function up(Schema $schema): void
+    {
+        // Note: this migration only works for entities that still exist. For others, it will not work but there is nothing we can do
+        $this->addSql('ALTER TABLE auditlog CHANGE cid cid VARCHAR(255) DEFAULT NULL COMMENT \'External contest ID associated to this entry\', CHANGE dataid dataid VARCHAR(64) DEFAULT NULL COMMENT \'(External) identifier in reference table\'');
+        $this->addSql('UPDATE auditlog INNER JOIN contest ON CAST(contest.cid AS CHAR) = auditlog.cid SET auditlog.cid = contest.externalid');
+        foreach (static::ENTITIES as $table => $fields) {
+            if (!is_array($fields)) {
+                $fields = [$fields];
+            }
+            foreach ($fields as $field) {
+                $this->addSql(sprintf(
+                    'UPDATE auditlog INNER JOIN %s ON CAST(%s.%s AS CHAR) = auditlog.dataid AND auditlog.datatype = "%s" SET auditlog.dataid = %s.externalid',
+                    $table, $table, $field, $table, $table
+                ));
+            }
+        }
+    }
+
+    public function down(Schema $schema): void
+    {
+        // Note: this migration only works for entities that still exist. For others, it will not work but there is nothing we can do
+        $this->addSql('UPDATE auditlog INNER JOIN contest ON contest.externalid = auditlog.cid SET auditlog.cid = contest.cid');
+        foreach (static::ENTITIES as $table => $fields) {
+            $field = is_array($fields) ? $fields[0] : $fields;
+            $this->addSql(sprintf(
+                'UPDATE auditlog INNER JOIN %s ON %s.externalid = auditlog.dataid AND auditlog.datatype = "%s" SET auditlog.dataid = %s.%s',
+                $table, $table, $table, $table, $field
+            ));
+        }
+        $this->addSql('ALTER TABLE auditlog CHANGE cid cid INT UNSIGNED DEFAULT NULL COMMENT \'Contest ID associated to this entry\', CHANGE dataid dataid VARCHAR(64) DEFAULT NULL COMMENT \'Identifier in reference table\'');
+    }
+
+    public function isTransactional(): bool
+    {
+        return false;
+    }
+}
diff --git a/webapp/public/js/domjudge.js b/webapp/public/js/domjudge.js
index 68d8a7373b..2f979eb5d5 100644
--- a/webapp/public/js/domjudge.js
+++ b/webapp/public/js/domjudge.js
@@ -998,14 +998,16 @@ function initializeKeyboardShortcuts() {
             var parts = window.location.href.split('/');
             var lastPart = parts[parts.length - 1];
             var params = lastPart.split('?');
-            var currentNumber = parseInt(params[0]);
-            if (isNaN(currentNumber)) {
-                return;
-            }
             if (key === 'j') {
-                parts[parts.length - 1] = currentNumber + 1;
+                if (!window.nextEntity) {
+                    return;
+                }
+                parts[parts.length - 1] = window.nextEntity;
             } else if (key === 'k') {
-                parts[parts.length - 1] = currentNumber - 1;
+                if (!window.previousEntity) {
+                    return;
+                }
+                parts[parts.length - 1] = window.previousEntity;
             }
             if (params.length > 1) {
                 parts[parts.length - 1] += '?' + params[1];
@@ -1039,9 +1041,13 @@ function initializeKeyboardShortcuts() {
                     sequence = '';
                     return;
                 }
-                if (e.key >= '0' && e.key <= '9') {
+                if (/^[a-zA-Z0-9_.-]$/.test(e.key)) {
                     sequence += e.key;
                     box.text(type + sequence);
+                } else if (e.key === 'Backspace') {
+                    e.preventDefault();
+                    sequence = sequence.slice(0, -1);
+                    box.text(type + sequence);
                 } else {
                     ignore = false;
                     if (box) {
@@ -1302,8 +1308,8 @@ function initScoreboardSubmissions() {
         const linkEl = e.currentTarget;
         e.preventDefault();
         const $modal = $('[data-submissions-modal] .modal').clone();
-        const $teamEl = $(`[data-team-external-id="${linkEl.dataset.teamId}"]`);
-        const $problemEl = $(`[data-problem-external-id="${linkEl.dataset.problemId}"]`);
+        const $teamEl = $(`tr[data-team-id="${linkEl.dataset.teamId}"]`);
+        const $problemEl = $(`th[data-problem-id="${linkEl.dataset.problemId}"]`);
         $modal.find('[data-team]').html($teamEl.data('teamName'));
         $modal.find('[data-problem-badge]').html($problemEl.data('problemBadge'));
         $modal.find('[data-problem-name]').html($problemEl.data('problemName'));
@@ -1403,7 +1409,7 @@ function initDiffEditor(editorId) {
         'onDiffSelectChange': (f) => {
             select.change((e) => {
                 const noDiff = e.target.value === "";
-                const submitId = parseInt(e.target.value);
+                const submitId = e.target.value;
                 f(submitId, noDiff);
             });
         }
@@ -1432,10 +1438,10 @@ function initDiffEditor(editorId) {
             diffTitle.style.display = 'inline';
             diffTag.innerText = selected.dataset.tag;
             diffLink.href = selected.dataset.url;
-            diffLink.innerText = `s${submitId}`;
+            diffLink.innerText = submitId;
         }
     };
-    updateSelect(parseInt(select[0].value), select[0].value === "");
+    updateSelect(select[0].value, select[0].value === "");
     editor.onDiffSelectChange(updateSelect);
 }
 
@@ -1559,7 +1565,7 @@ function initDiffEditorTab(editorId, diffId, submissionId, models) {
             return;
         }
 
-        const submitId = parseInt(editors[editorId].getDiffSelection());
+        const submitId = editors[editorId].getDiffSelection();
         const noDiff = editors[editorId].getDiffSelection() === "";
         if (noDiff) {
             setIcon('file');
diff --git a/webapp/src/Controller/API/BalloonController.php b/webapp/src/Controller/API/BalloonController.php
index 0ef708184b..6ae826dfe3 100644
--- a/webapp/src/Controller/API/BalloonController.php
+++ b/webapp/src/Controller/API/BalloonController.php
@@ -59,14 +59,14 @@ public function listAction(
         foreach ($balloonsData as $b) {
             /** @var Team $team */
             $team = $b['data']['team'];
-            $teamName = "t" . $team->getTeamid() . ": " . $team->getEffectiveName();
+            $teamName = $team->getExternalid() . ": " . $team->getEffectiveName();
             $balloons[] = new Balloon(
                 balloonid: $b['data']['balloonid'],
                 time: $b['data']['time'],
                 problem: $b['data']['problem'],
                 contestproblem: $b['data']['contestproblem'],
                 team: $teamName,
-                teamid: $team->getTeamid(),
+                teamid: $team->getExternalid(),
                 location: $b['data']['location'],
                 affiliation: $b['data']['affiliation'],
                 affiliationid: $b['data']['affiliationid'],
diff --git a/webapp/src/Controller/API/ClarificationController.php b/webapp/src/Controller/API/ClarificationController.php
index a502b64c82..6f9df8f8b6 100644
--- a/webapp/src/Controller/API/ClarificationController.php
+++ b/webapp/src/Controller/API/ClarificationController.php
@@ -249,7 +249,7 @@ public function addAction(
         $this->em->persist($clarification);
         $this->em->flush();
 
-        $this->dj->auditlog('clarification', $clarification->getClarid(), 'added', null, null, $contestId);
+        $this->dj->auditlog('clarification', $clarification->getExternalid(), 'added', null, null, $contest->getExternalid());
         $this->eventLogService->log('clarification', $clarification->getClarid(), 'create', $contestId);
 
         // Refresh the clarification since the event log service will have unloaded it.
diff --git a/webapp/src/Controller/API/JudgehostController.php b/webapp/src/Controller/API/JudgehostController.php
index e9b184606f..e1fe673604 100644
--- a/webapp/src/Controller/API/JudgehostController.php
+++ b/webapp/src/Controller/API/JudgehostController.php
@@ -114,7 +114,7 @@ public function getJudgehostsAction(
      * Add a new judgehost to the list of judgehosts.
      * Also restarts (and returns) unfinished judgings.
      *
-     * @return array<array{jobid: int, submitid: int}>
+     * @return array<array{jobid: int, submitid: string}>
      * @throws NonUniqueResultException
      */
     #[IsGranted('ROLE_JUDGEHOST')]
@@ -127,7 +127,7 @@ public function getJudgehostsAction(
             items: new OA\Items(
                 properties: [
                     new OA\Property(property: 'jobid', type: 'integer'),
-                    new OA\Property(property: 'submitid', type: 'integer'),
+                    new OA\Property(property: 'submitid', type: 'string'),
                 ],
                 type: 'object'
             )
@@ -188,7 +188,7 @@ public function createJudgehostAction(Request $request): array
 
         return array_map(fn(Judging $judging) => [
             'jobid' => $judging->getJudgingid(),
-            'submitid' => $judging->getSubmission()->getSubmitid(),
+            'submitid' => $judging->getSubmission()->getExternalid(),
         ], $judgings);
     }
 
@@ -442,8 +442,9 @@ public function updateJudgingAction(
 
                     $judgingId = $judging->getJudgingid();
                     $contestId = $judging->getSubmission()->getContest()->getCid();
-                    $this->dj->auditlog('judging', $judgingId, 'judged',
-                                        'compiler-error', $judgehost->getHostname(), $contestId);
+                    $contestExernalid = $judging->getSubmission()->getContest()->getExternalid();
+                    $this->dj->auditlog('judging', (string)$judgingId, 'judged',
+                                        'compiler-error', $judgehost->getHostname(), $contestExernalid);
 
                     $this->maybeUpdateActiveJudging($judging);
                     $this->em->flush();
@@ -459,8 +460,8 @@ public function updateJudgingAction(
                     $problem    = $submission->getProblem();
                     $this->scoreboardService->calculateScoreRow($contest, $team, $problem);
 
-                    $message = sprintf("submission %d, judging %d: compiler-error",
-                                       $submission->getSubmitid(), $judging->getJudgingid());
+                    $message = sprintf("submission %s, judging %d: compiler-error",
+                                       $submission->getExternalid(), $judging->getJudgingid());
                     $this->dj->alert('reject', $message);
                 });
             }
@@ -905,9 +906,9 @@ protected function giveBackJudging(int $judgingId, ?Judgehost $judgehost): void
                 $this->em->flush();
             }
 
-            $this->dj->auditlog('judging', $judgingId, 'given back'
+            $this->dj->auditlog('judging', (string)$judgingId, 'given back'
                 . ($judgehost === null ? '' : ' for judgehost ' . $judgehost->getHostname()), null,
-                $judgehost?->getHostname(), $judging->getContest()->getCid());
+                $judgehost?->getHostname(), $judging->getContest()->getExternalid());
         }
     }
 
@@ -1118,7 +1119,7 @@ private function addSingleJudgingRun(
                 // this means that these alert messages should be treated as
                 // confidential information.
                 $msg = sprintf("submission %s, judging %s: %s",
-                               $submission->getSubmitid(), $judging->getJudgingid(), $result);
+                               $submission->getExternalid(), $judging->getJudgingid(), $result);
                 $this->dj->alert($result === 'correct' ? 'accept' : 'reject', $msg);
 
                 // Potentially send a balloon, i.e. if no verification required (case of verification required is
@@ -1127,7 +1128,7 @@ private function addSingleJudgingRun(
                     $this->balloonService->updateBalloons($contest, $submission, $judging);
                 }
 
-                $this->dj->auditlog('judging', $judging->getJudgingid(), 'judged', $result, $hostname);
+                $this->dj->auditlog('judging', (string)$judging->getJudgingid(), 'judged', $result, $hostname);
             }
 
             // Send an event for an endtime (and max runtime update).
@@ -1223,7 +1224,7 @@ private function maybeUpdateActiveJudging(Judging $judging): void
      * @return JudgehostFile[]
      */
     #[IsGranted(new Expression("is_granted('ROLE_JURY') or is_granted('ROLE_JUDGEHOST')"))]
-    #[Rest\Get('/get_files/{type}/{id<\d+>}')]
+    #[Rest\Get('/get_files/{type}/{id}')]
     #[OA\Response(
         response: 200,
         description: 'The files for the submission, testcase or script.',
@@ -1270,7 +1271,7 @@ public function getVersionCommands(string $judgetaskid): array
         }
 
         $submission = $this->em->getRepository(Submission::class)
-            ->findOneBy(['submitid' => $judgeTask->getSubmitid()]);
+            ->findByExternalId($judgeTask->getSubmitid());
         if (!$submission) {
             throw new HttpException(500, 'Unknown submission with submitid ' . $judgeTask->getSubmitid());
         }
@@ -1334,7 +1335,7 @@ public function checkVersions(Request $request, string $judgetaskid): array
         }
 
         $submission = $this->em->getRepository(Submission::class)
-            ->findOneBy(['submitid' => $judgeTask->getSubmitid()]);
+            ->findByExternalId($judgeTask->getSubmitid());
         if (!$submission) {
             throw new BadRequestHttpException('Unknown submission with submitid ' . $judgeTask->getSubmitid());
         }
@@ -1418,7 +1419,8 @@ private function getSourceFiles(string $id): array
         $queryBuilder = $this->em->createQueryBuilder()
             ->from(SubmissionFile::class, 'f')
             ->select('f')
-            ->andWhere('f.submission = :submitid')
+            ->join('f.submission', 's')
+            ->andWhere('s.externalid = :submitid')
             ->setParameter('submitid', $id)
             ->orderBy('f.ranknumber');
 
@@ -1836,7 +1838,7 @@ private function getJudgetasks(string|int|null $jobId, int $max_batchsize, Judge
                 ->getQuery()
                 ->execute();
             $this->em->flush();
-            $this->dj->auditlog('queuetask', $jobId, 'deleted');
+            $this->dj->auditlog('queuetask', (string)$jobId, 'deleted');
         } else {
             return $this->serializeJudgeTasks($judgetasks, $judgehost);
         }
diff --git a/webapp/src/Controller/API/LanguageController.php b/webapp/src/Controller/API/LanguageController.php
index 7073e7bace..525b1cb5ab 100644
--- a/webapp/src/Controller/API/LanguageController.php
+++ b/webapp/src/Controller/API/LanguageController.php
@@ -82,7 +82,7 @@ public function singleAction(Request $request, string $id): Response
     #[OA\Parameter(ref: '#/components/parameters/id')]
     public function updateExecutableActions(Request $request, string $id): void
     {
-        $language = $this->em->getRepository(Language::class)->find($id);
+        $language = $this->em->getRepository(Language::class)->findByExternalId($id);
         if (!$language) {
             throw new BadRequestHttpException("Unknown language '$id'.");
         }
@@ -124,7 +124,7 @@ public function updateExecutableActions(Request $request, string $id): void
 
         $language->getCompileExecutable()->setImmutableExecutable($immutableExecutable);
         $this->em->flush();
-        $this->dj->auditlog('executable', $language->getLangid(), 'updated');
+        $this->dj->auditlog('executable', $language->getExternalid(), 'updated');
     }
 
     #[IsGranted('ROLE_ADMIN')]
diff --git a/webapp/src/Controller/API/PrintController.php b/webapp/src/Controller/API/PrintController.php
index 221e3a1864..e979fecbd7 100644
--- a/webapp/src/Controller/API/PrintController.php
+++ b/webapp/src/Controller/API/PrintController.php
@@ -80,10 +80,11 @@ public function printAsTeam(
     ): JsonResponse {
         $langid = null;
         if ($print->language !== null) {
+            /** @var string|null $langid */
             $langid = $this->em
                 ->createQueryBuilder()
                 ->from(Language::class, "l")
-                ->select("l.langid")
+                ->select("l.externalid")
                 ->andWhere("l.name = :name")
                 ->setParameter("name", $print->language)
                 ->getQuery()
diff --git a/webapp/src/Controller/API/ProblemController.php b/webapp/src/Controller/API/ProblemController.php
index 479c96b105..d00ad05f86 100644
--- a/webapp/src/Controller/API/ProblemController.php
+++ b/webapp/src/Controller/API/ProblemController.php
@@ -281,7 +281,7 @@ public function unlinkProblemAction(Request $request, string $id): Response
         }
 
         $this->em->remove($contestProblem);
-        $id = [$contestProblem->getCid(), $contestProblem->getProbid()];
+        $id = [$contestProblem->getExternalId(), $contestProblem->getExternalId()];
         $this->dj->auditlog('contest_problem', implode(', ', $id), 'deleted');
         $this->eventLogService->log('problem', $contestProblem->getProbid(),
                                     EventLogService::ACTION_DELETE, $cid,
@@ -354,7 +354,7 @@ public function linkProblemAction(
         $this->em->persist($contestProblem);
         $this->em->flush();
 
-        $fullId = [$contestProblem->getCid(), $contestProblem->getProbid()];
+        $fullId = [$contestProblem->getExternalId(), $contestProblem->getExternalId()];
         $this->dj->auditlog('contest_problem', implode(', ', $fullId), 'added');
         $this->eventLogService->log('problem', $contestProblem->getProbid(),
                                     EventLogService::ACTION_CREATE, $cid,
diff --git a/webapp/src/Controller/API/ScoreboardController.php b/webapp/src/Controller/API/ScoreboardController.php
index 51f0c23a3c..b0f1c6b672 100644
--- a/webapp/src/Controller/API/ScoreboardController.php
+++ b/webapp/src/Controller/API/ScoreboardController.php
@@ -64,7 +64,7 @@ public function __construct(
         name: 'category',
         description: 'Get the scoreboard for only this category',
         in: 'query',
-        schema: new OA\Schema(type: 'integer')
+        schema: new OA\Schema(type: 'string')
     )]
     #[OA\Parameter(
         name: 'country',
@@ -76,7 +76,7 @@ public function __construct(
         name: 'affiliation',
         description: 'Get the scoreboard for only this affiliation',
         in: 'query',
-        schema: new OA\Schema(type: 'integer')
+        schema: new OA\Schema(type: 'string')
     )]
     #[OA\Parameter(
         name: 'public',
@@ -93,11 +93,11 @@ public function __construct(
     public function getScoreboardAction(
         Request $request,
         #[MapQueryParameter]
-        ?int $category = null,
+        ?string $category = null,
         #[MapQueryParameter]
         ?string $country = null,
         #[MapQueryParameter]
-        ?int $affiliation = null,
+        ?string $affiliation = null,
         #[MapQueryParameter(name: 'allteams')]
         bool $allTeams = false,
         #[MapQueryParameter(name: 'public')]
diff --git a/webapp/src/Controller/API/UserController.php b/webapp/src/Controller/API/UserController.php
index e3135ce267..2315fca0be 100644
--- a/webapp/src/Controller/API/UserController.php
+++ b/webapp/src/Controller/API/UserController.php
@@ -410,7 +410,7 @@ protected function addOrUpdateUser(AddUser $addUser, Request $request): Response
 
         $this->em->persist($user);
         $this->em->flush();
-        $this->dj->auditlog('user', $user->getUserid(), 'added');
+        $this->dj->auditlog('user', $user->getExternalid(), 'added');
 
         return $this->renderCreateData($request, $user, 'user', $user->getUserid());
     }
diff --git a/webapp/src/Controller/BaseController.php b/webapp/src/Controller/BaseController.php
index 00b17e4424..a8c77e4703 100644
--- a/webapp/src/Controller/BaseController.php
+++ b/webapp/src/Controller/BaseController.php
@@ -8,6 +8,7 @@
 use App\Entity\Contest;
 use App\Entity\ContestProblem;
 use App\Entity\ExternalIdFromInternalIdInterface;
+use App\Entity\HasExternalIdInterface;
 use App\Entity\Problem;
 use App\Entity\RankCache;
 use App\Entity\ScoreCache;
@@ -151,7 +152,12 @@ protected function saveEntity(
             }
         }
 
-        $this->dj->auditlog($auditLogType, $id, $isNewEntity ? 'added' : 'updated');
+        if ($entity instanceof HasExternalIdInterface) {
+            $dataid = $entity->getExternalId();
+        } else {
+            $dataid = $id;
+        }
+        $this->dj->auditlog($auditLogType, (string)$dataid, $isNewEntity ? 'added' : 'updated');
     }
 
     /**
@@ -216,7 +222,12 @@ protected function commitDeleteEntity(object $entity, array $primaryKeyData): vo
 
         // Add an audit log entry.
         $auditLogType = Utils::tableForEntity($entity);
-        $this->dj->auditlog($auditLogType, implode(', ', $primaryKeyData), 'deleted');
+        if ($entity instanceof HasExternalIdInterface) {
+            $dataid = $entity->getExternalId();
+        } else {
+            $dataid = implode(', ', $primaryKeyData);
+        }
+        $this->dj->auditlog($auditLogType, $dataid, 'deleted');
 
         // Trigger the delete event. We need to do this before deleting the entity to make
         // sure we can still find the entity in the table.
@@ -296,7 +307,7 @@ protected function commitDeleteEntity(object $entity, array $primaryKeyData): vo
      * @param Object[] $entities
      * @param array<string, array<string, array{'target': string, 'targetColumn': string, 'type': string}>> $relations
      *
-     * @return array{0: bool, 1: array<int[]>, 2: string[]}
+     * @return array{0: bool, 1: array<int[]>, 2: string[], 3: array<string>}
      */
     protected function buildDeleteTree(array $entities, array $relations): array {
         $isError = false;
@@ -305,9 +316,13 @@ protected function buildDeleteTree(array $entities, array $relations): array {
         $readableType = str_replace('_', ' ', Utils::tableForEntity($entities[0]));
         $metadata = $this->em->getClassMetadata($entities[0]::class);
         $primaryKeyData = [];
+        $externalIdData = [];
         $messages = [];
         foreach ($entities as $entity) {
             $primaryKeyDataTemp = [];
+            if ($entity instanceof HasExternalIdInterface) {
+                $externalIdData[] = $entity->getExternalId();
+            }
             foreach ($metadata->getIdentifierColumnNames() as $primaryKeyColumn) {
                 $primaryKeyColumnValue = $propertyAccessor->getValue($entity, $primaryKeyColumn);
                 $primaryKeyDataTemp[] = $primaryKeyColumnValue;
@@ -372,7 +387,7 @@ protected function buildDeleteTree(array $entities, array $relations): array {
             }
             $primaryKeyData[] = $primaryKeyDataTemp;
         }
-        return [$isError, $primaryKeyData, array_values(array_unique($messages))];
+        return [$isError, $primaryKeyData, array_values(array_unique($messages)), $externalIdData];
     }
 
     /**
@@ -404,6 +419,7 @@ protected function deleteEntities(
             $isError,
             $primaryKeyData,
             $deleteTreeMessages,
+            $externalIdData,
         ] = $this->buildDeleteTree($entities, $relations);
         if (!empty($deleteTreeMessages)) {
             $messages = $deleteTreeMessages;
@@ -419,7 +435,7 @@ protected function deleteEntities(
                 $this->commitDeleteEntity($entity, $primaryKeyData[$id]);
                 $description = $entity->getShortDescription();
                 $msgList[] = sprintf('Successfully deleted %s %s "%s"',
-                    $readableType, implode(', ', $primaryKeyData[$id]), $description);
+                    $readableType, $externalIdData[$id] ?? implode(', ', $primaryKeyData[$id]), $description);
             }
 
             $msg = implode("\n", $msgList);
@@ -438,7 +454,7 @@ protected function deleteEntities(
 
         $data = [
             'type' => $readableType,
-            'primaryKey' => implode(', ', array_merge(...$primaryKeyData)),
+            'primaryKey' => !empty($externalIdData) ? implode(', ', $externalIdData) : implode(', ', array_merge(...$primaryKeyData)),
             'description' => implode(',', $descriptions),
             'messages' => $messages,
             'isError' => $isError,
@@ -547,7 +563,7 @@ protected function addEntityCheckbox(array &$data, object $entity, mixed $identi
                     '<input type="checkbox" name="ids[]" value="%s" class="%s">',
                     $identifierValue,
                     $checkboxClass
-                )
+                ),
             ];
         }
     }
@@ -649,4 +665,120 @@ protected function processAddFormForExternalIdEntity(
 
         return null;
     }
+
+    /**
+     * Get the previous and next object IDs for navigation.
+     *
+     * @param class-string                $entityClass     Entity class to query
+     * @param mixed                       $currentIdValue  Current value of the ID field
+     * @param string                      $idField         Field to return as the ID (e.g., 'externalid', 'submitid')
+     * @param array<string, 'ASC'|'DESC'> $orderBy         Sort criteria as field => direction (e.g., ['e.submittime' => 'ASC', 'e.submitid' => 'ASC'])
+     * @param bool                        $filterOnContest Whether to filter results by current contests
+     *
+     * @return array{previous: string|int|null, next: string|int|null}
+     */
+    protected function getPreviousAndNextObjectIds(
+        string $entityClass,
+        mixed $currentIdValue,
+        string $idField = 'externalid',
+        array $orderBy = ['e.externalid' => 'ASC'],
+        bool $filterOnContest = false,
+    ): array {
+        $result = ['previous' => null, 'next' => null];
+
+        // Fetch the current entity once to get field values
+        $currentEntity = $this->em->getRepository($entityClass)->findOneBy([$idField => $currentIdValue]);
+        if ($currentEntity === null) {
+            return $result;
+        }
+
+        $accessor = PropertyAccess::createPropertyAccessor();
+
+        // Pre-compute field values for comparison
+        $fieldValues = [];
+        foreach (array_keys($orderBy) as $field) {
+            $fieldName = str_replace('e.', '', $field);
+            $fieldValues[$field] = $accessor->getValue($currentEntity, $fieldName);
+        }
+
+        // Build the comparison conditions based on the sort criteria.
+        // For multi-column ordering, we need: (col1 < val1) OR (col1 = val1 AND col2 < val2) etc.
+        $buildComparisonConditions = function (string $operator) use ($orderBy, $fieldValues): array {
+            $conditions = [];
+            $parameters = [];
+            $fields = array_keys($orderBy);
+            $directions = array_values($orderBy);
+
+            for ($i = 0; $i < count($fields); $i++) {
+                $equalityParts = [];
+                // Add equality conditions for all previous columns
+                for ($j = 0; $j < $i; $j++) {
+                    $field = $fields[$j];
+                    $paramName = 'eq_' . $j;
+                    $equalityParts[] = "$field = :$paramName";
+                    $parameters[$paramName] = $fieldValues[$field];
+                }
+
+                // Add the comparison for this column
+                $field = $fields[$i];
+                $direction = $directions[$i];
+                // For "previous": if ASC, we want < ; if DESC, we want >
+                // For "next": if ASC, we want > ; if DESC, we want <
+                $compOp = ($operator === 'previous')
+                    ? ($direction === 'ASC' ? '<' : '>')
+                    : ($direction === 'ASC' ? '>' : '<');
+                $paramName = 'cmp_' . $i;
+                $comparisonPart = "$field $compOp :$paramName";
+                $parameters[$paramName] = $fieldValues[$field];
+
+                if (!empty($equalityParts)) {
+                    $conditions[] = '(' . implode(' AND ', $equalityParts) . ' AND ' . $comparisonPart . ')';
+                } else {
+                    $conditions[] = '(' . $comparisonPart . ')';
+                }
+            }
+
+            return ['condition' => implode(' OR ', $conditions), 'parameters' => $parameters];
+        };
+
+        foreach (['previous', 'next'] as $direction) {
+            $qb = $this->em->createQueryBuilder()
+                ->select("e.$idField")
+                ->from($entityClass, 'e');
+
+            // Build and apply the comparison conditions
+            $comp = $buildComparisonConditions($direction);
+            if (!empty($comp['condition'])) {
+                $qb->andWhere($comp['condition']);
+                foreach ($comp['parameters'] as $param => $value) {
+                    $qb->setParameter($param, $value);
+                }
+            }
+
+            // Apply contest filter
+            if ($filterOnContest && $contest = $this->dj->getCurrentContest()) {
+                $qb->andWhere('e.contest = :contest')
+                    ->setParameter('contest', $contest);
+            }
+
+            // Apply ordering (reversed for previous)
+            foreach ($orderBy as $field => $dir) {
+                $actualDir = $direction === 'previous'
+                    ? ($dir === 'ASC' ? 'DESC' : 'ASC')
+                    : $dir;
+                $qb->addOrderBy($field, $actualDir);
+            }
+
+            $qb->setMaxResults(1);
+
+            try {
+                $value = $qb->getQuery()->getSingleScalarResult();
+                $result[$direction] = $value;
+            } catch (NoResultException) {
+                // No previous/next found, leave as null
+            }
+        }
+
+        return $result;
+    }
 }
diff --git a/webapp/src/Controller/Jury/AnalysisController.php b/webapp/src/Controller/Jury/AnalysisController.php
index 26fa10b436..8d4bf6c97d 100644
--- a/webapp/src/Controller/Jury/AnalysisController.php
+++ b/webapp/src/Controller/Jury/AnalysisController.php
@@ -55,12 +55,12 @@ public function indexAction(
         $delayedJudgings = $em->createQueryBuilder()
             ->from(Submission::class, 's')
             ->innerJoin(Judging::class, 'j', Expr\Join::WITH, 's.submitid = j.submission')
-            ->select('s.submitid, MIN(j.judgingid) AS judgingid, s.submittime, MIN(j.starttime) - s.submittime AS timediff, COUNT(j.judgingid) AS num_judgings')
+            ->select('s.externalid as submitexternalid, MIN(j.judgingid) AS judgingid, s.submittime, MIN(j.starttime) - s.submittime AS timediff, COUNT(j.judgingid) AS num_judgings')
             ->andWhere('s.contest = :contest')
             ->setParameter('contest', $contest)
             ->andWhere('s.team IN (:teams)')
             ->setParameter('teams', $teams)
-            ->groupBy('s.submitid')
+            ->groupBy('s.externalid')
             ->andHaving('timediff > :timediff')
             ->setParameter('timediff', $delayedTimeDiff)
             ->orderBy('timediff', 'DESC')
@@ -83,8 +83,10 @@ public function indexAction(
     }
 
     #[Route(path: '/team/{team}', name: 'analysis_team')]
-    public function teamAction(Team $team): Response
-    {
+    public function teamAction(
+        #[MapEntity(mapping: ['team' => 'externalid'])]
+        Team $team,
+    ): Response {
         $contest = $this->dj->getCurrentContest();
 
         if ($contest === null) {
@@ -100,7 +102,7 @@ public function teamAction(Team $team): Response
 
     #[Route(path: '/problem/{probid}', name: 'analysis_problem')]
     public function problemAction(
-        #[MapEntity(id: 'probid')]
+        #[MapEntity(mapping: ['probid' => 'externalid'])]
         Problem $problem,
         #[MapQueryParameter]
         ?string $view = null
diff --git a/webapp/src/Controller/Jury/AuditLogController.php b/webapp/src/Controller/Jury/AuditLogController.php
index ad000bc413..ec1d670958 100644
--- a/webapp/src/Controller/Jury/AuditLogController.php
+++ b/webapp/src/Controller/Jury/AuditLogController.php
@@ -79,7 +79,7 @@ public function indexAction(
 
             $cid = $logline->getCid();
             if ($cid) {
-                    $data['where']['value'] = "c" . $cid;
+                    $data['where']['value'] = $cid;
                     $data['where']['sortvalue'] = $cid;
                     $data['where']['link'] = $this->generateUrl('jury_contest', ['contestId' => $cid]);
             } else {
@@ -148,11 +148,6 @@ private function generateDatatypeUrl(string $type, int|string|null $id): ?string
             case 'team_category':
                 return $this->generateUrl('jury_team_category', ['categoryId' => $id]);
             case 'user':
-                // Pre 6.1, usernames were stored instead of numeric IDs.
-                if (!is_numeric($id)) {
-                    $user = $this->em->getRepository(User::class)->findOneBy(['username'=>$id]);
-                    $id = $user->getUserId();
-                }
                 return $this->generateUrl('jury_user', ['userId' => $id]);
             case 'testcase':
                 // For testcase audit logs, the ID is actually the problem ID
diff --git a/webapp/src/Controller/Jury/BalloonController.php b/webapp/src/Controller/Jury/BalloonController.php
index 9098772310..1520e54c2f 100644
--- a/webapp/src/Controller/Jury/BalloonController.php
+++ b/webapp/src/Controller/Jury/BalloonController.php
@@ -88,7 +88,7 @@ public function indexAction(BalloonService $balloonService): Response
             $filteredAffiliations = $this->em->createQueryBuilder()
                 ->from(TeamAffiliation::class, 'a')
                 ->select('a')
-                ->where('a.affilid IN (:affilIds)')
+                ->where('a.externalid IN (:affilIds)')
                 ->setParameter('affilIds', $filters['affiliation-id'])
                 ->getQuery()
                 ->getResult();
@@ -123,7 +123,7 @@ public function indexAction(BalloonService $balloonService): Response
             $filteredCategories = $this->em->createQueryBuilder()
                 ->from(TeamCategory::class, 'c')
                 ->select('c')
-                ->where('c.categoryid IN (:categories)')
+                ->where('c.externalid IN (:categories)')
                 ->setParameter('categories', $filters['category-id'])
                 ->getQuery()
                 ->getResult();
@@ -131,7 +131,7 @@ public function indexAction(BalloonService $balloonService): Response
             $availableCategories = $this->em->createQueryBuilder()
                 ->from(TeamCategory::class, 'c')
                 ->select('c')
-                ->where('c.categoryid NOT IN (:categories)')
+                ->where('c.externalid NOT IN (:categories)')
                 ->setParameter('categories', $filters['category-id'])
                 ->getQuery()
                 ->getResult();
@@ -145,11 +145,11 @@ public function indexAction(BalloonService $balloonService): Response
         }
         $defaultCategories = $this->em->createQueryBuilder()
             ->from(TeamCategory::class, 'c')
-            ->select('c.categoryid')
+            ->select('c.externalid')
             ->where('c.visible = true')
             ->getQuery()
             ->getArrayResult();
-        $defaultCategories = array_column($defaultCategories, "categoryid");
+        $defaultCategories = array_column($defaultCategories, "externalid");
 
         return $this->render('jury/balloons.html.twig', [
             'refresh' => [
diff --git a/webapp/src/Controller/Jury/ClarificationController.php b/webapp/src/Controller/Jury/ClarificationController.php
index 4eda5224e2..6268b7b081 100644
--- a/webapp/src/Controller/Jury/ClarificationController.php
+++ b/webapp/src/Controller/Jury/ClarificationController.php
@@ -2,6 +2,7 @@
 
 namespace App\Controller\Jury;
 
+use App\Controller\BaseController;
 use App\Entity\Clarification;
 use App\Entity\Contest;
 use App\Entity\Problem;
@@ -20,19 +21,23 @@
 use Symfony\Component\HttpFoundation\Response;
 use Symfony\Component\HttpKernel\Attribute\MapQueryParameter;
 use Symfony\Component\HttpKernel\Exception\NotFoundHttpException;
+use Symfony\Component\HttpKernel\KernelInterface;
 use Symfony\Component\Routing\Attribute\Route;
 use Symfony\Component\Security\Http\Attribute\IsGranted;
 
 #[IsGranted('ROLE_CLARIFICATION_RW')]
 #[Route(path: '/jury/clarifications')]
-class ClarificationController extends AbstractController
+class ClarificationController extends BaseController
 {
     public function __construct(
-        protected readonly EntityManagerInterface $em,
-        protected readonly DOMJudgeService $dj,
+        EntityManagerInterface $em,
+        DOMJudgeService $dj,
         protected readonly ConfigurationService $config,
-        protected readonly EventLogService $eventLogService
-    ) {}
+        EventLogService $eventLogService,
+        KernelInterface $kernel,
+    ) {
+        parent::__construct($em, $eventLogService, $dj, $kernel);
+    }
 
     #[Route(path: '', name: 'jury_clarifications')]
     public function indexAction(
@@ -43,12 +48,12 @@ public function indexAction(
     ): Response {
         $categories = $this->config->get('clar_categories');
         if ($contest = $this->dj->getCurrentContest()) {
-            $contestIds = [$contest->getCid()];
+            $contestIds = [$contest->getExternalid()];
         } else {
             $contestIds = array_keys($this->dj->getCurrentContests());
-            // cid -1 will never happen, but otherwise the array is empty and that is not supported.
+            // cid @ will never happen, but otherwise the array is empty and that is not supported.
             if (empty($contestIds)) {
-                $contestIds = [-1];
+                $contestIds = ['@'];
             }
         }
 
@@ -59,9 +64,10 @@ public function indexAction(
         $queryBuilder = $this->em->createQueryBuilder()
             ->from(Clarification::class, 'clar')
             ->leftJoin('clar.problem', 'p')
+            ->innerJoin('clar.contest', 'c')
             ->leftJoin('p.contest_problems', 'cp', Join::WITH, 'cp.contest = clar.contest')
             ->select('clar', 'p', 'cp')
-            ->andWhere('clar.contest in (:contestIds)')
+            ->andWhere('c.externalid in (:contestIds)')
             ->setParameter('contestIds', $contestIds)
             ->orderBy('clar.submittime', 'DESC')
             ->addOrderBy('clar.clarid', 'DESC');
@@ -113,10 +119,10 @@ public function indexAction(
         ]);
     }
 
-    #[Route(path: '/{id<\d+>}', name: 'jury_clarification')]
-    public function viewAction(Request $request, int $id): Response
+    #[Route(path: '/{id}', name: 'jury_clarification')]
+    public function viewAction(Request $request, string $id): Response
     {
-        $clarification = $this->em->getRepository(Clarification::class)->find($id);
+        $clarification = $this->em->getRepository(Clarification::class)->findByExternalId($id);
         if (!$clarification) {
             throw new NotFoundHttpException(sprintf('Clarification with ID %s not found', $id));
         }
@@ -132,9 +138,14 @@ public function viewAction(Request $request, int $id): Response
 
         $parameters = ['list' => []];
 
+        if ($clarification->getProblem()?->getExternalid()) {
+            $subject = sprintf('%s|%s', $clarification->getContest()->getExternalid(), $clarification->getProblem()->getExternalid());
+        } else {
+            $subject = sprintf('%s#%s', $clarification->getContest()->getExternalid(), $clarification->getCategory());
+        }
         $formData = [
             'recipient' => JuryClarificationType::RECIPIENT_MUST_SELECT,
-            'subject' => sprintf('%s-%s', $clarification->getContest()->getCid(), $clarification->getProblem()?->getProbid() ?? $clarification->getCategory()),
+            'subject' => $subject,
         ];
         if ($clarification->getRecipient()) {
             $formData['recipient'] = $clarification->getRecipient()->getTeamid();
@@ -194,14 +205,14 @@ public function viewAction(Request $request, int $id): Response
             $data['subjectlink'] = null;
             if ($clar->getProblem()) {
                 if ($clar->getContestProblem()) {
-                    $concernssubject = $contest->getCid() . "-" . $clar->getProblem()->getProbid();
+                    $concernssubject = $contest->getExternalid() . "|" . $clar->getProblem()->getExternalid();
                 } else {
                     // Very special case, this problem is unlinked.
                     $concernssubject = "";
                 }
-                $data['subjectlink'] = $this->generateUrl('jury_problem', ['probId' => $clar->getProblem()->getProbid()]);
+                $data['subjectlink'] = $this->generateUrl('jury_problem', ['probId' => $clar->getProblem()->getExternalid()]);
             } elseif ($clar->getCategory()) {
-                $concernssubject = $contest->getCid() . "-" . $clar->getCategory();
+                $concernssubject = $contest->getExternalid() . "#" . $clar->getCategory();
             } else {
                 $concernssubject = "";
             }
@@ -230,10 +241,15 @@ public function viewAction(Request $request, int $id): Response
             ->getQuery()
             ->getSingleResult()['jury_member'];
 
+        $parameters['previousNext'] = $this->getPreviousAndNextObjectIds(
+            Clarification::class,
+            $clarification->getExternalid(),
+        );
+
         return $this->render('jury/clarification.html.twig', $parameters);
     }
 
-    #[Route(path: '/send', name: 'jury_clarification_new')]
+    #[Route(path: '/send', name: 'jury_clarification_new', priority: 1)]
     public function composeClarificationAction(
         Request $request,
         #[MapQueryParameter]
@@ -256,12 +272,12 @@ public function composeClarificationAction(
         return $this->render('jury/clarification_new.html.twig', ['form' => $form->createView()]);
     }
 
-    #[Route(path: '/{clarId<\d+>}/claim', name: 'jury_clarification_claim')]
-    public function toggleClaimAction(Request $request, int $clarId): Response
+    #[Route(path: '/{clarId}/claim', name: 'jury_clarification_claim')]
+    public function toggleClaimAction(Request $request, string $clarId): Response
     {
-        $clarification = $this->em->getReference(Clarification::class, $clarId);
+        $clarification = $this->em->getRepository(Clarification::class)->findByExternalId($clarId);
         if (!$clarification) {
-            throw new NotFoundHttpException(sprintf('Clarification with ID %d not found', $clarId));
+            throw new NotFoundHttpException(sprintf('Clarification with ID %s not found', $clarId));
         }
 
         if ($request->request->getBoolean('claimed')) {
@@ -275,12 +291,12 @@ public function toggleClaimAction(Request $request, int $clarId): Response
         }
     }
 
-    #[Route(path: '/{clarId<\d+>}/set-answered', name: 'jury_clarification_set_answered')]
-    public function toggleAnsweredAction(Request $request, int $clarId): Response
+    #[Route(path: '/{clarId}/set-answered', name: 'jury_clarification_set_answered')]
+    public function toggleAnsweredAction(Request $request, string $clarId): Response
     {
-        $clarification = $this->em->getReference(Clarification::class, $clarId);
+        $clarification = $this->em->getRepository(Clarification::class)->findByExternalId($clarId);
         if (!$clarification) {
-            throw new NotFoundHttpException(sprintf('Clarification with ID %d not found', $clarId));
+            throw new NotFoundHttpException(sprintf('Clarification with ID %s not found', $clarId));
         }
 
         $answered = $request->request->getBoolean('answered');
@@ -294,27 +310,33 @@ public function toggleAnsweredAction(Request $request, int $clarId): Response
         }
     }
 
-    #[Route(path: '/{clarId<\d+>}/change-subject', name: 'jury_clarification_change_subject')]
-    public function changeSubjectAction(Request $request, int $clarId): Response
+    #[Route(path: '/{clarId}/change-subject', name: 'jury_clarification_change_subject')]
+    public function changeSubjectAction(Request $request, string $clarId): Response
     {
-        $clarification = $this->em->getReference(Clarification::class, $clarId);
+        $clarification = $this->em->getRepository(Clarification::class)->findByExternalId($clarId);
         if (!$clarification) {
-            throw new NotFoundHttpException(sprintf('Clarification with ID %d not found', $clarId));
+            throw new NotFoundHttpException(sprintf('Clarification with ID %s not found', $clarId));
         }
 
         $subject = $request->request->get('subject');
-        [$cid, $probid] = explode('-', $subject);
+        $problemId = null;
+        $category = null;
+        if (str_contains($subject, '#')) {
+            [$cid, $category] = explode('#', $subject);
+        } else {
+            [$cid, $problemId] = explode('|', $subject);
+        }
 
-        $contest = $this->em->getReference(Contest::class, $cid);
+        $contest = $this->em->getRepository(Contest::class)->findByExternalId($cid);
         $clarification->setContest($contest);
 
-        if (ctype_digit($probid)) {
-            $problem = $this->em->getReference(Problem::class, $probid);
+        if ($problemId) {
+            $problem = $this->em->getRepository(Problem::class)->findByExternalId($problemId);
             $clarification->setProblem($problem);
             $clarification->setCategory(null);
         } else {
             $clarification->setProblem(null);
-            $clarification->setCategory($probid);
+            $clarification->setCategory($category);
         }
 
         $this->em->flush();
@@ -322,10 +344,10 @@ public function changeSubjectAction(Request $request, int $clarId): Response
         return $this->redirectToRoute('jury_clarification', ['id' => $clarId]);
     }
 
-    #[Route(path: '/{clarId<\d+>}/change-queue', name: 'jury_clarification_change_queue')]
-    public function changeQueueAction(Request $request, int $clarId): Response
+    #[Route(path: '/{clarId}/change-queue', name: 'jury_clarification_change_queue')]
+    public function changeQueueAction(Request $request, string $clarId): Response
     {
-        $clarification = $this->em->getReference(Clarification::class, $clarId);
+        $clarification = $this->em->getRepository(Clarification::class)->findByExternalId($clarId);
         if (!$clarification) {
             throw new NotFoundHttpException(sprintf('Clarification with ID %d not found', $clarId));
         }
@@ -363,25 +385,31 @@ protected function processSubmittedClarification(
         if (empty($recipient)) {
             $recipient = null;
         } else {
-            $team = $this->em->getReference(Team::class, $recipient);
+            $team = $this->em->getRepository(Team::class)->findByExternalId($recipient);
             $clarification->setRecipient($team);
         }
 
 
         $subject = $formData['subject'];
-        [$cid, $probid] = explode('-', $subject);
+        $problemId = null;
+        $category = null;
+        if (str_contains($subject, '#')) {
+            [$cid, $category] = explode('#', $subject);
+        } else {
+            [$cid, $problemId] = explode('|', $subject);
+        }
 
-        $contest = $this->em->getReference(Contest::class, $cid);
+        $contest = $this->em->getRepository(Contest::class)->findByExternalId($cid);
         $clarification->setContest($contest);
 
-        if (ctype_digit($probid)) {
-            $problem = $this->em->getReference(Problem::class, $probid);
+        if ($problemId) {
+            $problem = $this->em->getRepository(Problem::class)->findByExternalId($problemId);
             $clarification->setProblem($problem);
             $clarification->setCategory(null);
         } else {
             $clarification->setProblem(null);
-            if ($probid !== "") {
-                $clarification->setCategory($probid);
+            if ($category !== "") {
+                $clarification->setCategory($category);
             } else {
                 $clarification->setCategory(null);
             }
@@ -410,8 +438,8 @@ protected function processSubmittedClarification(
         $this->em->flush();
 
         $clarId = $clarification->getClarId();
-        $this->dj->auditlog('clarification', $clarId, 'added', null, null, $cid);
-        $this->eventLogService->log('clarification', $clarId, 'create', (int)$cid);
+        $this->dj->auditlog('clarification', $clarification->getExternalid(), 'added', null, null, $contest->getExternalid());
+        $this->eventLog->log('clarification', $clarId, 'create', $contest->getCid());
         // Reload clarification to make sure we have a fresh one after calling the event log service.
         $clarification = $this->em->getRepository(Clarification::class)->find($clarId);
 
diff --git a/webapp/src/Controller/Jury/ContestController.php b/webapp/src/Controller/Jury/ContestController.php
index b8c4c5e419..6625286ce6 100644
--- a/webapp/src/Controller/Jury/ContestController.php
+++ b/webapp/src/Controller/Jury/ContestController.php
@@ -81,8 +81,7 @@ public function indexAction(Request $request): Response
             ->getQuery()->getResult();
 
         $table_fields = [
-            'cid'             => ['title' => 'CID', 'sort' => true],
-            'externalid'      => ['title' => "external ID", 'sort' => true],
+            'externalid'      => ['title' => "ID", 'sort' => true],
             'shortname'       => ['title' => 'shortname', 'sort' => true],
             'name'            => ['title' => 'name', 'sort' => true],
             'scoreboard_type' => ['title' => 'scoreboard type', 'sort' => true],
@@ -151,7 +150,7 @@ public function indexAction(Request $request): Response
                     'icon' => 'file-' . $contest->getContestProblemsetType(),
                     'title' => 'view contest problemset document',
                     'link' => $this->generateUrl('jury_contest_problemset', [
-                        'cid' => $contest->getCid(),
+                        'cid' => $contest->getExternalid(),
                     ])
                 ];
             } else {
@@ -170,14 +169,14 @@ public function indexAction(Request $request): Response
                         'icon' => 'edit',
                         'title' => 'edit this contest',
                         'link' => $this->generateUrl('jury_contest_edit', [
-                            'contestId' => $contest->getCid(),
+                            'contestId' => $contest->getExternalid(),
                         ])
                     ];
                     $contestactions[] = [
                         'icon' => 'trash-alt',
                         'title' => 'delete this contest',
                         'link' => $this->generateUrl('jury_contest_delete', [
-                            'contestId' => $contest->getCid(),
+                            'contestId' => $contest->getExternalid(),
                         ]),
                         'ajaxModal' => true,
                     ];
@@ -275,13 +274,13 @@ public function indexAction(Request $request): Response
             if (!$contest->getEnabled()) {
                 $styles[] = 'disabled';
             }
-            if (in_array($contest->getCid(), array_keys($currentContests))) {
+            if (in_array($contest->getExternalid(), array_keys($currentContests))) {
                 $styles[] = 'highlight';
             }
             $contests_table[] = [
                 'data' => $contestdata,
                 'actions' => $contestactions,
-                'link' => $this->generateUrl('jury_contest', ['contestId' => $contest->getCid()]),
+                'link' => $this->generateUrl('jury_contest', ['contestId' => $contest->getExternalid()]),
                 'cssclass' => implode(' ', $styles),
             ];
         }
@@ -305,10 +304,10 @@ public function indexAction(Request $request): Response
         ]);
     }
 
-    #[Route(path: '/{contestId<\d+>}', name: 'jury_contest')]
-    public function viewAction(Request $request, int $contestId): Response
+    #[Route(path: '/{contestId}', name: 'jury_contest')]
+    public function viewAction(Request $request, string $contestId): Response
     {
-        $contest = $this->em->getRepository(Contest::class)->find($contestId);
+        $contest = $this->em->getRepository(Contest::class)->findByExternalId($contestId);
         if (!$contest) {
             throw new NotFoundHttpException(sprintf('Contest with ID %s not found', $contestId));
         }
@@ -353,6 +352,10 @@ public function viewAction(Request $request, int $contestId): Response
 
         return $this->render('jury/contest.html.twig', [
             'contest' => $contest,
+            'previousNext' => $this->getPreviousAndNextObjectIds(
+                Contest::class,
+                $contest->getExternalid(),
+            ),
             'allowRemovedIntervals' => $this->getParameter('removed_intervals'),
             'removedIntervalForm' => $form,
             'removedIntervals' => $removedIntervals,
@@ -368,7 +371,7 @@ public function toggleSubmitAction(
         string $contestId,
         string $type
     ): Response {
-        $contest = $this->em->getRepository(Contest::class)->find($contestId);
+        $contest = $this->em->getRepository(Contest::class)->findByExternalId($contestId);
         if (!$contest) {
             throw new NotFoundHttpException(sprintf('Contest with ID %s not found', $contestId));
         }
@@ -401,7 +404,7 @@ public function toggleSubmitAction(
         }
         $this->em->flush();
 
-        $this->dj->auditlog('contest', $contestId, $label, $value ? 'yes' : 'no');
+        $this->dj->auditlog('contest', $contest->getExternalid(), $label, $value ? 'yes' : 'no');
         return $this->redirectToLocalReferrer(
             $router,
             $request,
@@ -409,10 +412,10 @@ public function toggleSubmitAction(
         );
     }
 
-    #[Route(path: '/{contestId<\d+>}/remove-interval/{intervalId}', name: 'jury_contest_remove_interval', methods: ['POST'])]
-    public function removeIntervalAction(int $contestId, int $intervalId): RedirectResponse
+    #[Route(path: '/{contestId}/remove-interval/{intervalId}', name: 'jury_contest_remove_interval', methods: ['POST'])]
+    public function removeIntervalAction(string $contestId, int $intervalId): RedirectResponse
     {
-        $contest = $this->em->getRepository(Contest::class)->find($contestId);
+        $contest = $this->em->getRepository(Contest::class)->findByExternalId($contestId);
         if (!$contest) {
             throw new NotFoundHttpException(sprintf('Contest with ID %s not found', $contestId));
         }
@@ -437,14 +440,14 @@ public function removeIntervalAction(int $contestId, int $intervalId): RedirectR
         $this->addFlash('scoreboard_refresh',
             'After removing a removed time interval, it is ' .
             'necessary to recalculate any cached scoreboards.');
-        return $this->redirectToRoute('jury_contest', ['contestId' => $contest->getCid()]);
+        return $this->redirectToRoute('jury_contest', ['contestId' => $contest->getExternalid()]);
     }
 
     #[IsGranted('ROLE_ADMIN')]
-    #[Route(path: '/{contestId<\d+>}/edit', name: 'jury_contest_edit')]
-    public function editAction(Request $request, int $contestId): Response
+    #[Route(path: '/{contestId}/edit', name: 'jury_contest_edit')]
+    public function editAction(Request $request, string $contestId): Response
     {
-        $contest = $this->em->getRepository(Contest::class)->find($contestId);
+        $contest = $this->em->getRepository(Contest::class)->findByExternalId($contestId);
         if (!$contest) {
             throw new NotFoundHttpException(sprintf('Contest with ID %s not found', $contestId));
         }
@@ -466,7 +469,7 @@ public function editAction(Request $request, int $contestId): Response
             if ($problems = $contestData['problems'] ?? null) {
                 $existingProblemIndices = [];
                 foreach ($contest->getProblems() as $index => $problem) {
-                    $existingProblemIndices[$problem->getProbId()] = $index;
+                    $existingProblemIndices[$problem->getExternalId()] = $index;
                 }
                 $indexForNew = $contest->getProblems()->count();
                 $newProblems = [];
@@ -566,7 +569,7 @@ public function editAction(Request $request, int $contestId): Response
                 $this->eventLogService->log('problems', $problem->getProbid(),
                     EventLogService::ACTION_DELETE, $contest->getCid(), null, null, false);
             }
-            return $this->redirectToRoute('jury_contest', ['contestId' => $contest->getcid()]);
+            return $this->redirectToRoute('jury_contest', ['contestId' => $contest->getExternalId()]);
         }
 
         $this->em->refresh($contest);
@@ -578,10 +581,10 @@ public function editAction(Request $request, int $contestId): Response
     }
 
     #[IsGranted('ROLE_ADMIN')]
-    #[Route(path: '/{contestId<\d+>}/delete', name: 'jury_contest_delete')]
-    public function deleteAction(Request $request, int $contestId): Response
+    #[Route(path: '/{contestId}/delete', name: 'jury_contest_delete')]
+    public function deleteAction(Request $request, string $contestId): Response
     {
-        $contest = $this->em->getRepository(Contest::class)->find($contestId);
+        $contest = $this->em->getRepository(Contest::class)->findByExternalId($contestId);
         if (!$contest) {
             throw new NotFoundHttpException(sprintf('Contest with ID %s not found', $contestId));
         }
@@ -595,13 +598,10 @@ public function deleteAction(Request $request, int $contestId): Response
     }
 
     #[IsGranted('ROLE_ADMIN')]
-    #[Route(path: '/{contestId<\d+>}/problems/{probId<\d+>}/delete', name: 'jury_contest_problem_delete')]
-    public function deleteProblemAction(Request $request, int $contestId, int $probId): Response
+    #[Route(path: '/{contestId}/problems/{probId}/delete', name: 'jury_contest_problem_delete')]
+    public function deleteProblemAction(Request $request, string $contestId, string $probId): Response
     {
-        $contestProblem = $this->em->getRepository(ContestProblem::class)->find([
-            'contest' => $contestId,
-            'problem' => $probId
-        ]);
+        $contestProblem = $this->em->getRepository(ContestProblem::class)->findByProblemAndContest($contestId, $probId);
         if (!$contestProblem) {
             throw new NotFoundHttpException(
                 sprintf('Contest problem with contest ID %s and problem ID %s not found',
@@ -618,7 +618,7 @@ public function deleteProblemAction(Request $request, int $contestId, int $probI
     }
 
     #[IsGranted('ROLE_ADMIN')]
-    #[Route(path: '/add', name: 'jury_contest_add')]
+    #[Route(path: '/add', name: 'jury_contest_add', priority: 1)]
     public function addAction(Request $request): Response
     {
         $contest = new Contest();
@@ -631,7 +631,7 @@ public function addAction(Request $request): Response
 
         if ($response = $this->processAddFormForExternalIdEntity(
             $form, $contest,
-            fn () => $this->generateUrl('jury_contest', ['contestId' => $contest->getcid()]),
+            fn () => $this->generateUrl('jury_contest', ['contestId' => $contest->getExternalid()]),
             function () use ($form, $contest) {
                 $response = $this->checkTimezones($form);
                 if ($response !== null) {
@@ -675,12 +675,12 @@ function () use ($form, $contest) {
         ]);
     }
 
-    #[Route(path: '/{contestId<\d+>}/prefetch', name: 'jury_contest_prefetch')]
-    public function prefetchAction(Request $request, int $contestId): Response
+    #[Route(path: '/{contestId}/prefetch', name: 'jury_contest_prefetch')]
+    public function prefetchAction(Request $request, string $contestId): Response
     {
-        $contest  = $this->em->getRepository(Contest::class)->find($contestId);
+        $contest  = $this->em->getRepository(Contest::class)->findByExternalId($contestId);
         if ($contest === null) {
-            throw new BadRequestHttpException("Contest with cid=$contestId not found.");
+            throw new BadRequestHttpException("Contest with ID $contestId not found.");
         }
         $judgehosts = $this->em->getRepository(Judgehost::class)->findBy([
             'enabled' => true,
@@ -756,11 +756,11 @@ public function prefetchAction(Request $request, int $contestId): Response
     }
 
     #[IsGranted('ROLE_ADMIN')]
-    #[Route(path: '/{contestId<\d+>}/finalize', name: 'jury_contest_finalize')]
-    public function finalizeAction(Request $request, int $contestId): Response
+    #[Route(path: '/{contestId}/finalize', name: 'jury_contest_finalize')]
+    public function finalizeAction(Request $request, string $contestId): Response
     {
         /** @var Contest $contest */
-        $contest  = $this->em->getRepository(Contest::class)->find($contestId);
+        $contest  = $this->em->getRepository(Contest::class)->findByExternalId($contestId);
         $blockers = [];
         if (Utils::difftime((float)$contest->getEndtime(), Utils::now()) > 0) {
             $blockers[] = sprintf('Contest not ended yet (will end at %s)',
@@ -771,24 +771,24 @@ public function finalizeAction(Request $request, int $contestId): Response
         $submissionIds = array_map(fn(array $data) => $data['submitid'], $this->em->createQueryBuilder()
             ->from(Submission::class, 's')
             ->join('s.judgings', 'j', Join::WITH, 'j.valid = 1')
-            ->select('s.submitid')
+            ->select('s.externalid')
             ->andWhere('s.contest = :contest')
             ->andWhere('s.valid = true')
             ->andWhere('j.result IS NULL')
             ->setParameter('contest', $contest)
-            ->orderBy('s.submitid')
+            ->orderBy('s.externalid')
             ->getQuery()
             ->getResult()
         );
 
         if (count($submissionIds) > 0) {
-            $blockers[] = 'Unjudged submissions found: s' . implode(', s', $submissionIds);
+            $blockers[] = 'Unjudged submissions found: ' . implode(', ', $submissionIds);
         }
 
         /** @var int[] $clarificationIds */
         $clarificationIds = array_map(fn(array $data) => $data['clarid'], $this->em->createQueryBuilder()
             ->from(Clarification::class, 'c')
-            ->select('c.clarid')
+            ->select('c.externalid')
             ->andWhere('c.contest = :contest')
             ->andWhere('c.answered = false')
             ->setParameter('contest', $contest)
@@ -810,9 +810,9 @@ public function finalizeAction(Request $request, int $contestId): Response
             if ($form->isSubmitted() && $form->isValid()) {
                 $contest->setFinalizetime(Utils::now());
                 $this->em->flush();
-                $this->dj->auditlog('contest', $contest->getCid(), 'finalized',
+                $this->dj->auditlog('contest', $contest->getExternalid(), 'finalized',
                                                  $contest->getFinalizecomment());
-                return $this->redirectToRoute('jury_contest', ['contestId' => $contest->getCid()]);
+                return $this->redirectToRoute('jury_contest', ['contestId' => $contest->getExternalid()]);
             }
         }
 
@@ -824,14 +824,14 @@ public function finalizeAction(Request $request, int $contestId): Response
     }
 
     #[IsGranted('ROLE_ADMIN')]
-    #[Route(path: '/{contestId<\d+>}/{time}/doNow', name: 'jury_contest_donow')]
-    public function doNowAction(Request $request, int $contestId, string $time): Response
+    #[Route(path: '/{contestId}/{time}/doNow', name: 'jury_contest_donow')]
+    public function doNowAction(Request $request, string $contestId, string $time): Response
     {
         $times         = ['activate', 'start', 'freeze', 'end', 'unfreeze', 'finalize', 'deactivate'];
         $start_actions = ['delay_start', 'resume_start'];
         $actions       = array_merge($times, $start_actions);
 
-        $contest = $this->em->getRepository(Contest::class)->find($contestId);
+        $contest = $this->em->getRepository(Contest::class)->findByExternalId($contestId);
         if (!$contest) {
             throw new NotFoundHttpException(sprintf('Contest with ID %s not found', $contestId));
         }
@@ -841,12 +841,12 @@ public function doNowAction(Request $request, int $contestId, string $time): Res
         }
 
         if ($time === 'finalize') {
-            return $this->redirectToRoute('jury_contest_finalize', ['contestId' => $contest->getCid()]);
+            return $this->redirectToRoute('jury_contest_finalize', ['contestId' => $contest->getExternalid()]);
         }
 
         $now       = (int)floor(Utils::now());
         $nowstring = date('Y-m-d H:i:s ', $now) . date_default_timezone_get();
-        $this->dj->auditlog('contest', $contest->getCid(), $time . ' now', $nowstring);
+        $this->dj->auditlog('contest', $contest->getExternalid(), $time . ' now', $nowstring);
 
         // Special case delay/resume start (only sets/unsets starttime_undefined).
         $maxSeconds = Contest::STARTTIME_UPDATE_MIN_SECONDS_BEFORE;
@@ -919,10 +919,10 @@ public function doNowAction(Request $request, int $contestId, string $time): Res
         return $this->redirectToRoute('jury_contests');
     }
 
-    #[Route(path: '/{contestId<\d+>}/request-remaining', name: 'jury_contest_request_remaining')]
-    public function requestRemainingRunsWholeContestAction(int $contestId): RedirectResponse
+    #[Route(path: '/{contestId}/request-remaining', name: 'jury_contest_request_remaining')]
+    public function requestRemainingRunsWholeContestAction(string $contestId): RedirectResponse
     {
-        $contest = $this->em->getRepository(Contest::class)->find($contestId);
+        $contest = $this->em->getRepository(Contest::class)->findByExternalId($contestId);
         if (!$contest) {
             throw new NotFoundHttpException(sprintf('Contest with ID %s not found', $contestId));
         }
@@ -930,13 +930,10 @@ public function requestRemainingRunsWholeContestAction(int $contestId): Redirect
         return $this->redirectToRoute('jury_contest', ['contestId' => $contestId]);
     }
 
-    #[Route(path: '/{contestId<\d+>}/problems/{probId<\d+>}/request-remaining', name: 'jury_contest_problem_request_remaining')]
-    public function requestRemainingRunsContestProblemAction(int $contestId, int $probId): RedirectResponse
+    #[Route(path: '/{contestId}/problems/{probId}/request-remaining', name: 'jury_contest_problem_request_remaining')]
+    public function requestRemainingRunsContestProblemAction(string $contestId, string $probId): RedirectResponse
     {
-        $contestProblem = $this->em->getRepository(ContestProblem::class)->find([
-            'contest' => $contestId,
-            'problem' => $probId
-        ]);
+        $contestProblem = $this->em->getRepository(ContestProblem::class)->findByProblemAndContest($contestId, $probId);
         if (!$contestProblem) {
             throw new NotFoundHttpException(
                 sprintf('Contest problem with contest ID %s and problem ID %s not found',
@@ -987,23 +984,23 @@ private function checkTimezones(FormInterface $form): ?Response
     }
 
     #[IsGranted('ROLE_ADMIN')]
-    #[Route(path: '/{contestId<\d+>}/lock', name: 'jury_contest_lock')]
-    public function lockAction(Request $request, int $contestId): Response
+    #[Route(path: '/{contestId}/lock', name: 'jury_contest_lock')]
+    public function lockAction(Request $request, string $contestId): Response
     {
         return $this->doLock($contestId, true);
     }
 
     #[IsGranted('ROLE_ADMIN')]
-    #[Route(path: '/{contestId<\d+>}/unlock', name: 'jury_contest_unlock')]
-    public function unlockAction(Request $request, int $contestId): Response
+    #[Route(path: '/{contestId}/unlock', name: 'jury_contest_unlock')]
+    public function unlockAction(Request $request, string $contestId): Response
     {
         return $this->doLock($contestId, false);
     }
 
-    #[Route(path: '/{contestId<\d+>}/samples.zip', name: 'jury_contest_samples_data_zip')]
-    public function samplesDataZipAction(Request $request, int $contestId): Response
+    #[Route(path: '/{contestId}/samples.zip', name: 'jury_contest_samples_data_zip')]
+    public function samplesDataZipAction(Request $request, string $contestId): Response
     {
-        $contest = $this->em->getRepository(Contest::class)->find($contestId);
+        $contest = $this->em->getRepository(Contest::class)->findByExternalId($contestId);
         if (!$contest) {
             throw new NotFoundHttpException(sprintf('Contest with ID %s not found', $contestId));
         }
@@ -1011,14 +1008,14 @@ public function samplesDataZipAction(Request $request, int $contestId): Response
         return $this->dj->getSamplesZipForContest($contest);
     }
 
-    private function doLock(int $contestId, bool $locked): Response
+    private function doLock(string $contestId, bool $locked): Response
     {
-        $contest = $this->em->getRepository(Contest::class)->find($contestId);
+        $contest = $this->em->getRepository(Contest::class)->findByExternalId($contestId);
         if (!$contest) {
             throw new NotFoundHttpException(sprintf('Contest with ID %s not found.', $contestId));
         }
 
-        $this->dj->auditlog('contest', $contest->getCid(), $locked ? 'lock' : 'unlock');
+        $this->dj->auditlog('contest', $contest->getExternalid(), $locked ? 'lock' : 'unlock');
         $contest->setIsLocked($locked);
         $this->em->flush();
 
@@ -1030,25 +1027,25 @@ private function doLock(int $contestId, bool $locked): Response
         return $this->redirectToRoute('jury_contest', ['contestId' => $contestId]);
     }
 
-    #[Route(path: '/{contestId<\d+>}/{type<public|unfrozen>}-scoreboard.zip', name: 'jury_scoreboard_data_zip')]
+    #[Route(path: '/{contestId}/{type<public|unfrozen>}-scoreboard.zip', name: 'jury_scoreboard_data_zip')]
     public function scoreboardDataZipAction(
-        int $contestId,
+        string $contestId,
         string $type,
         RequestStack $requestStack,
         Request $request,
         ScoreboardService $scoreboardService
     ): Response {
-        $contest = $this->em->getRepository(Contest::class)->find($contestId);
+        $contest = $this->em->getRepository(Contest::class)->findByExternalId($contestId);
         if (!$contest) {
             throw new NotFoundHttpException(sprintf('Contest with ID %s not found', $contestId));
         }
         return $this->dj->getScoreboardZip($request, $requestStack, $contest, $scoreboardService, $type === 'unfrozen');
     }
 
-    #[Route(path: '/{cid<\d+>}/problemset', name: 'jury_contest_problemset')]
-    public function viewProblemsetAction(int $cid): StreamedResponse
+    #[Route(path: '/{cid}/problemset', name: 'jury_contest_problemset')]
+    public function viewProblemsetAction(string $cid): StreamedResponse
     {
-        $contest = $this->em->getRepository(Contest::class)->find($cid);
+        $contest = $this->em->getRepository(Contest::class)->findByExternalId($cid);
         if (!$contest) {
             throw new NotFoundHttpException(sprintf('Contest with ID %s not found', $cid));
         }
diff --git a/webapp/src/Controller/Jury/ExecutableController.php b/webapp/src/Controller/Jury/ExecutableController.php
index 27a6c32ebc..c2c60bf9c8 100644
--- a/webapp/src/Controller/Jury/ExecutableController.php
+++ b/webapp/src/Controller/Jury/ExecutableController.php
@@ -368,6 +368,12 @@ public function viewAction(
             'uploadForm' => $uploadForm->createView(),
             'selected' => $index,
             'executable' => $executable,
+            'previousNext' => $this->getPreviousAndNextObjectIds(
+                Executable::class,
+                $executable->getExecid(),
+                'execid',
+                ['e.execid' => 'ASC'],
+            ),
             'default_compare' => (string)$this->config->get('default_compare'),
             'default_run' => (string)$this->config->get('default_run'),
             'default_full_debug' => (string)$this->config->get('default_full_debug'),
diff --git a/webapp/src/Controller/Jury/ImportExportController.php b/webapp/src/Controller/Jury/ImportExportController.php
index 6f07dfd71a..ad0df070cb 100644
--- a/webapp/src/Controller/Jury/ImportExportController.php
+++ b/webapp/src/Controller/Jury/ImportExportController.php
@@ -168,7 +168,7 @@ public function indexAction(Request $request): Response
                 );
                 $allMessages = array_merge($allMessages, $messages);
                 if ($newProblem) {
-                    $this->dj->auditlog('problem', $newProblem->getProbid(), 'upload zip',
+                    $this->dj->auditlog('problem', $newProblem->getExternalid(), 'upload zip',
                         $clientName);
                 } else {
                     $this->postMessages($allMessages);
@@ -184,7 +184,7 @@ public function indexAction(Request $request): Response
             $this->postMessages($allMessages);
 
             if ($newProblem !== null) {
-                return $this->redirectToRoute('jury_problem', ['probId' => $newProblem->getProbid()]);
+                return $this->redirectToRoute('jury_problem', ['probId' => $newProblem->getExternalid()]);
             } else {
                 return $this->redirectToRoute('jury_problems');
             }
@@ -400,7 +400,7 @@ protected function getResultsHtml(
             ->getResult();
         $categoryIds = [];
         foreach ($categories as $category) {
-            $categoryIds[] = $category->getCategoryid();
+            $categoryIds[] = $category->getExternalid();
         }
 
         $contest = $this->dj->getCurrentContest();
@@ -416,7 +416,7 @@ protected function getResultsHtml(
 
         $teamNames = [];
         foreach ($teams as $team) {
-            $teamNames[$team->getIcpcId()] = $team->getEffectiveName();
+            $teamNames[$team->getIcpcId() ?? $team->getExternalid()] = $team->getEffectiveName();
         }
 
         $awarded       = [];
@@ -496,8 +496,8 @@ protected function getResultsHtml(
                     $firstToSolve[$problem->getProbid()] = [
                         'problem' => $problem->getShortname(),
                         'problem_name' => $problem->getProblem()->getName(),
-                        'team' => $teamNames[$team->getIcpcId()],
-                        'rank' => $rankPerTeam[$team->getIcpcId()] ?: '-',
+                        'team' => $teamNames[$team->getIcpcId() ?? $team->getExternalid()],
+                        'rank' => $rankPerTeam[$team->getIcpcId() ?? $team->getExternalid()] ?: '-',
                         'time' => Utils::scoretime($matrixItem->time, $scoreIsInSeconds),
                     ];
                 }
@@ -574,7 +574,7 @@ protected function getClarificationsHtml(): Response
                 if (!isset($grouped[$queue])) {
                     $grouped[$queue] = [];
                 }
-                $grouped[$queue][$clarification->getClarid()] = $clarification;
+                $grouped[$queue][$clarification->getExternalid()] = $clarification;
             }
         }
 
diff --git a/webapp/src/Controller/Jury/InternalErrorController.php b/webapp/src/Controller/Jury/InternalErrorController.php
index 04642dab40..919d569415 100644
--- a/webapp/src/Controller/Jury/InternalErrorController.php
+++ b/webapp/src/Controller/Jury/InternalErrorController.php
@@ -7,6 +7,7 @@
 use App\Entity\InternalError;
 use App\Entity\Judgehost;
 use App\Entity\JudgeTask;
+use App\Entity\Language;
 use App\Entity\Problem;
 use App\Service\DOMJudgeService;
 use App\Service\EventLogService;
@@ -102,8 +103,8 @@ public function viewAction(int $errorId): Response
         $affectedLink = $affectedText = null;
         switch ($disabled['kind']) {
             case 'problem':
-                $affectedLink = $this->generateUrl('jury_problem', ['probId' => $disabled['probid']]);
                 $problem      = $this->em->getRepository(Problem::class)->find($disabled['probid']);
+                $affectedLink = $this->generateUrl('jury_problem', ['probId' => $problem->getExternalid()]);
                 $affectedText = $problem->getName();
                 break;
             case 'judgehost':
@@ -117,8 +118,9 @@ public function viewAction(int $errorId): Response
                 }
                 break;
             case 'language':
-                $affectedLink = $this->generateUrl('jury_language', ['langId' => $disabled['langid']]);
-                $affectedText = $disabled['langid'];
+                $language     = $this->em->getRepository(Language::class)->find($disabled['langid']);
+                $affectedLink = $this->generateUrl('jury_language', ['langId' => $language->getExternalid()]);
+                $affectedText = $language->getName();
                 break;
             case 'executable':
                 $affectedLink = $this->generateUrl('jury_executable', ['execId' => $disabled['execid']]);
@@ -151,7 +153,7 @@ public function handleAction(Request $request, ?Profiler $profiler, int $errorId
             ->getSingleResult();
         if ($action === 'ignore') {
             $internalError->setStatus(InternalErrorStatusType::STATUS_IGNORED);
-            $this->dj->auditlog('internal_error', $internalError->getErrorid(),
+            $this->dj->auditlog('internal_error', (string)$internalError->getErrorid(),
                 sprintf('internal error: %s', InternalErrorStatusType::STATUS_IGNORED));
             $this->em->flush();
             return $this->redirectToRoute('jury_internal_error', ['errorId' => $internalError->getErrorid()]);
@@ -175,7 +177,7 @@ public function handleAction(Request $request, ?Profiler $profiler, int $errorId
                 );
                 $this->em->flush();
 
-                $this->dj->auditlog('internal_error', $internalError->getErrorid(),
+                $this->dj->auditlog('internal_error', (string)$internalError->getErrorid(),
                     sprintf('internal error: %s', InternalErrorStatusType::STATUS_RESOLVED));
 
                 $affectedJudgings = $internalError->getAffectedJudgings();
diff --git a/webapp/src/Controller/Jury/JudgeRemainingTrait.php b/webapp/src/Controller/Jury/JudgeRemainingTrait.php
index 8466616198..e1419be140 100644
--- a/webapp/src/Controller/Jury/JudgeRemainingTrait.php
+++ b/webapp/src/Controller/Jury/JudgeRemainingTrait.php
@@ -79,7 +79,7 @@ protected function judgeRemainingJudgings(array $judgings): void
         }
     }
 
-    public function judgeRemaining(int $contestId = -1, string $categoryId = '', string|int $probId = '', string $langId = ''): void
+    public function judgeRemaining(?string $contestId = null, ?string $categoryId = null, ?string $probId = null, ?string $langId = null): void
     {
         $query = $this->em->createQueryBuilder()
             ->from(Judging::class, 'j')
@@ -90,24 +90,27 @@ public function judgeRemaining(int $contestId = -1, string $categoryId = '', str
             ->andWhere('j.valid = true')
             ->andWhere('j.result != :compiler_error')
             ->setParameter('compiler_error', 'compiler-error');
-        if ($contestId > -1) {
+        if ($contestId !== null) {
             $query
-                ->andWhere('s.contest = :contestId')
+                ->join('s.contest', 'c')
+                ->andWhere('c.externalid = :contestId')
                 ->setParameter('contestId', $contestId);
         }
-        if ($categoryId > -1) {
+        if ($categoryId !== null) {
             $query
-                ->andWhere('tc.categoryid = :categoryId')
+                ->andWhere('tc.externalid = :categoryId')
                 ->setParameter('categoryId', $categoryId);
         }
-        if ($probId !== '') {
+        if ($probId !== null) {
             $query
-                ->andWhere('s.problem = :probId')
+                ->join('s.problem', 'p')
+                ->andWhere('p.externalid = :probId')
                 ->setParameter('probId', $probId);
         }
-        if ($langId !== '') {
+        if ($langId !== null) {
             $query
-                ->andWhere('s.language = :langId')
+                ->join('s.language', 'l')
+                ->andWhere('l.externalid = :langId')
                 ->setParameter('langId', $langId);
         }
         $judgings = $query->getQuery()->getResult();
diff --git a/webapp/src/Controller/Jury/JudgehostController.php b/webapp/src/Controller/Jury/JudgehostController.php
index 3679c196b2..84c49c4772 100644
--- a/webapp/src/Controller/Jury/JudgehostController.php
+++ b/webapp/src/Controller/Jury/JudgehostController.php
@@ -280,6 +280,12 @@ public function viewAction(Request $request, int $judgehostid): Response
 
         $data = [
             'judgehost' => $judgehost,
+            'previousNext' => $this->getPreviousAndNextObjectIds(
+                Judgehost::class,
+                $judgehost->getJudgehostid(),
+                'judgehostid',
+                ['e.judgehostid' => 'ASC'],
+            ),
             'status' => $status,
             'statusIcon' => $statusIcon,
             'judgings' => $judgings,
@@ -325,7 +331,7 @@ public function enableAction(RouterInterface $router, Request $request, int $jud
         $judgehost = $this->em->getRepository(Judgehost::class)->find($judgehostid);
         $judgehost->setEnabled(true);
         $this->em->flush();
-        $this->dj->auditlog('judgehost', $judgehost->getJudgehostid(), 'marked enabled');
+        $this->dj->auditlog('judgehost', (string)$judgehost->getJudgehostid(), 'marked enabled');
         return $this->redirectToLocalReferrer($router, $request, $this->generateUrl('jury_judgehosts'));
     }
 
@@ -337,7 +343,7 @@ public function disableAction(RouterInterface $router, Request $request, int $ju
         $judgehost = $this->em->getRepository(Judgehost::class)->find($judgehostid);
         $judgehost->setEnabled(false);
         $this->em->flush();
-        $this->dj->auditlog('judgehost', $judgehost->getJudgehostid(), 'marked disabled');
+        $this->dj->auditlog('judgehost', (string)$judgehost->getJudgehostid(), 'marked disabled');
         return $this->redirectToLocalReferrer($router, $request, $this->generateUrl('jury_judgehosts'));
     }
 
diff --git a/webapp/src/Controller/Jury/JuryMiscController.php b/webapp/src/Controller/Jury/JuryMiscController.php
index 9f64a3994f..df6d62a455 100644
--- a/webapp/src/Controller/Jury/JuryMiscController.php
+++ b/webapp/src/Controller/Jury/JuryMiscController.php
@@ -85,7 +85,7 @@ public function ajaxDataAction(Request $request, string $datatype): JsonResponse
 
         if ($datatype === 'affiliations') {
             $affiliations = $qb->from(TeamAffiliation::class, 'a')
-                ->select('a.affilid', 'a.name', 'a.shortname')
+                ->select('a.externalid', 'a.name', 'a.shortname')
                 ->where($qb->expr()->like('a.name', '?1'))
                 ->orWhere($qb->expr()->like('a.shortname', '?1'))
                 ->orWhere($qb->expr()->eq('a.affilid', '?2'))
@@ -95,9 +95,9 @@ public function ajaxDataAction(Request $request, string $datatype): JsonResponse
                 ->getResult();
 
             $results = array_map(function (array $affiliation) {
-                $displayname = $affiliation['name'] . " (" . $affiliation['affilid'] . ")";
+                $displayname = $affiliation['name'] . " (" . $affiliation['externalid'] . ")";
                 return [
-                    'id' => $affiliation['affilid'],
+                    'id' => $affiliation['externalid'],
                     'text' => $displayname,
                 ];
             }, $affiliations);
@@ -117,7 +117,7 @@ public function ajaxDataAction(Request $request, string $datatype): JsonResponse
             throw new AccessDeniedHttpException('Permission denied');
         } elseif ($datatype === 'problems') {
             $problems = $qb->from(Problem::class, 'p')
-                ->select('p.probid', 'p.name')
+                ->select('p.externalid', 'p.name')
                 ->where($qb->expr()->like('p.name', '?1'))
                 ->orWhere($qb->expr()->eq('p.probid', '?2'))
                 ->orderBy('p.name', 'ASC')
@@ -126,15 +126,15 @@ public function ajaxDataAction(Request $request, string $datatype): JsonResponse
                 ->getResult();
 
             $results = array_map(function (array $problem) {
-                $displayname = $problem['name'] . " (p" . $problem['probid'] . ")";
+                $displayname = $problem['name'] . " (" . $problem['externalid'] . ")";
                 return [
-                    'id' => $problem['probid'],
+                    'id' => $problem['externalid'],
                     'text' => $displayname,
                 ];
             }, $problems);
         } elseif ($datatype === 'teams') {
             $teams = $qb->from(Team::class, 't')
-                ->select('t.teamid', 't.display_name', 't.name', 'COALESCE(t.display_name, t.name) AS order')
+                ->select('t.externalid', 't.display_name', 't.name', 'COALESCE(t.display_name, t.name) AS order')
                 ->where($qb->expr()->like('t.name', '?1'))
                 ->orWhere($qb->expr()->like('t.display_name', '?1'))
                 ->orWhere($qb->expr()->eq('t.teamid', '?2'))
@@ -144,32 +144,32 @@ public function ajaxDataAction(Request $request, string $datatype): JsonResponse
                 ->getResult();
 
             $results = array_map(function (array $team) {
-                $displayname = ($team['display_name'] ?? $team['name']) . " (t" . $team['teamid'] . ")";
+                $displayname = ($team['display_name'] ?? $team['name']) . " (" . $team['externalid'] . ")";
                 return [
-                    'id' => $team['teamid'],
+                    'id' => $team['externalid'],
                     'text' => $displayname,
                 ];
             }, $teams);
         } elseif ($datatype === 'languages') {
             $languages = $qb->from(Language::class, 'l')
-                ->select('l.langid', 'l.name')
+                ->select('l.externalid', 'l.name')
                 ->where($qb->expr()->like('l.name', '?1'))
-                ->orWhere($qb->expr()->eq('l.langid', '?2'))
+                ->orWhere($qb->expr()->eq('l.externalid', '?2'))
                 ->orderBy('l.name', 'ASC')
                 ->getQuery()->setParameter(1, '%' . $q . '%')
                 ->setParameter(2, $q)
                 ->getResult();
 
             $results = array_map(function (array $language) {
-                $displayname = $language['name'] . " (" . $language['langid'] . ")";
+                $displayname = $language['name'] . " (" . $language['externalid'] . ")";
                 return [
-                    'id' => $language['langid'],
+                    'id' => $language['externalid'],
                     'text' => $displayname,
                 ];
             }, $languages);
         } elseif ($datatype === 'contests') {
             $query = $qb->from(Contest::class, 'c')
-                ->select('c.cid', 'c.name', 'c.shortname')
+                ->select('c.externalid', 'c.name', 'c.shortname')
                 ->where($qb->expr()->like('c.name', '?1'))
                 ->orWhere($qb->expr()->like('c.shortname', '?1'))
                 ->orWhere($qb->expr()->eq('c.cid', '?2'))
@@ -187,9 +187,9 @@ public function ajaxDataAction(Request $request, string $datatype): JsonResponse
             $contests = $query->getResult();
 
             $results = array_map(function (array $contest) {
-                $displayname = $contest['name'] . " (" . $contest['shortname'] . " - c" . $contest['cid'] . ")";
+                $displayname = $contest['name'] . " (" . $contest['shortname'] . " - " . $contest['externalid'] . ")";
                 return [
-                    'id' => $contest['cid'],
+                    'id' => $contest['externalid'],
                     'text' => $displayname,
                 ];
             }, $contests);
@@ -215,7 +215,7 @@ public function refreshCacheAction(Request $request, ScoreboardService $scoreboa
             $contests = [$cid => $contests[$cid]];
         } elseif ($request->cookies->has('domjudge_cid') &&
                   ($contest = $this->dj->getCurrentContest())) {
-            $contests = [$contest->getCid() => $contest];
+            $contests = [$contest->getExternalid() => $contest];
         }
 
         if ($request->isXmlHttpRequest() && $request->isMethod('POST')) {
@@ -288,7 +288,7 @@ public function judgingVerifierAction(Request $request): Response
             $judging         = $submission->getJudgings()->first();
             /** @var string[] $expectedResults */
             $expectedResults = $submission->getExpectedResults();
-            $submissionId    = $submission->getSubmitid();
+            $submissionId    = $submission->getExternalid();
             $submissionFiles = $submission->getFiles();
 
             $result = mb_strtoupper($judging->getResult());
@@ -340,20 +340,20 @@ public function judgingVerifierAction(Request $request): Response
             'nomatch' => $nomatch,
             'earlier' => $earlier,
             'problems' => $problems,
-            'contestId' => $this->dj->getCurrentContest()?->getCid(),
+            'contestId' => $this->dj->getCurrentContest()?->getExternalid(),
             'verifyMultiple' => $verifyMultiple,
         ]);
     }
 
-    #[Route(path: '/change-contest/{contestId<-?\d+>}', name: 'jury_change_contest')]
-    public function changeContestAction(Request $request, RouterInterface $router, int $contestId): Response
+    #[Route(path: '/change-contest/{contestId}', name: 'jury_change_contest')]
+    public function changeContestAction(Request $request, RouterInterface $router, string $contestId): Response
     {
         if ($this->isLocalReferer($router, $request)) {
             $response = new RedirectResponse($request->headers->get('referer'));
         } else {
             $response = $this->redirectToRoute('jury_index');
         }
-        return $this->dj->setCookie('domjudge_cid', (string)$contestId, 0, null, '', false, false,
+        return $this->dj->setCookie('domjudge_cid', $contestId, 0, null, '', false, false,
                                                  $response);
     }
 
diff --git a/webapp/src/Controller/Jury/LanguageController.php b/webapp/src/Controller/Jury/LanguageController.php
index f9c3981834..e714052926 100644
--- a/webapp/src/Controller/Jury/LanguageController.php
+++ b/webapp/src/Controller/Jury/LanguageController.php
@@ -52,8 +52,7 @@ public function indexAction(): Response
             ->orderBy('lang.name', 'ASC')
             ->getQuery()->getResult();
         $table_fields = [
-            'langid' => ['title' => 'ID', 'sort' => true],
-            'externalid' => ['title' => 'external ID', 'sort' => true],
+            'externalid' => ['title' => 'ID', 'sort' => true],
             'name' => ['title' => 'name', 'sort' => true, 'default_sort' => true],
             'entrypoint' => ['title' => 'entry point', 'sort' => true],
             'allowjudge' => ['title' => 'allow judge', 'sort' => true],
@@ -80,14 +79,14 @@ public function indexAction(): Response
                     'icon' => 'edit',
                     'title' => 'edit this language',
                     'link' => $this->generateUrl('jury_language_edit', [
-                        'langId' => $lang->getLangid()
+                        'langId' => $lang->getExternalid()
                     ])
                 ];
                 $langactions[] = [
                     'icon' => 'trash-alt',
                     'title' => 'delete this language',
                     'link' => $this->generateUrl('jury_language_delete', [
-                        'langId' => $lang->getLangid(),
+                        'langId' => $lang->getExternalid(),
                     ]),
                     'ajaxModal' => true,
                 ];
@@ -126,14 +125,14 @@ public function indexAction(): Response
                 $enabled_languages[] = [
                     'data' => $langdata,
                     'actions' => $langactions,
-                    'link' => $this->generateUrl('jury_language', ['langId' => $lang->getLangid()]),
+                    'link' => $this->generateUrl('jury_language', ['langId' => $lang->getExternalid()]),
                     'cssclass' => '',
                 ];
             } else {
                 $disabled_languages[] = [
                     'data' => $langdata,
                     'actions' => $langactions,
-                    'link' => $this->generateUrl('jury_language', ['langId' => $lang->getLangid()]),
+                    'link' => $this->generateUrl('jury_language', ['langId' => $lang->getExternalid()]),
                     'cssclass' => 'disabled',
                 ];
             }
@@ -145,10 +144,8 @@ public function indexAction(): Response
         ]);
     }
 
-    // Note that the add action appears before the view action to make sure
-    // /add is not seen as a language.
     #[IsGranted('ROLE_ADMIN')]
-    #[Route(path: '/add', name: 'jury_language_add')]
+    #[Route(path: '/add', name: 'jury_language_add', priority: 1)]
     public function addAction(Request $request): Response
     {
         $language = new Language();
@@ -159,7 +156,7 @@ public function addAction(Request $request): Response
 
         if ($response = $this->processAddFormForExternalIdEntity(
             $form, $language,
-            fn() => $this->generateUrl('jury_language', ['langId' => $language->getLangid()]),
+            fn() => $this->generateUrl('jury_language', ['langId' => $language->getExternalid()]),
             function () use ($language) {
                 // Normalize extensions
                 if ($language->getExtensions()) {
@@ -187,7 +184,7 @@ function () use ($language) {
     #[Route(path: '/{langId}', name: 'jury_language')]
     public function viewAction(Request $request, SubmissionService $submissionService, string $langId): Response
     {
-        $language = $this->em->getRepository(Language::class)->find($langId);
+        $language = $this->em->getRepository(Language::class)->findByExternalId($langId);
         if (!$language) {
             throw new NotFoundHttpException(sprintf('Language with ID %s not found', $langId));
         }
@@ -201,13 +198,17 @@ public function viewAction(Request $request, SubmissionService $submissionServic
 
         $data = [
             'language' => $language,
+            'previousNext' => $this->getPreviousAndNextObjectIds(
+                Language::class,
+                $language->getExternalid(),
+            ),
             'submissions' => $submissions,
             'submissionCounts' => $submissionCounts,
             'showContest' => count($this->dj->getCurrentContests(honorCookie: true)) > 1,
             'showExternalResult' => $this->dj->shadowMode(),
             'refresh' => [
                 'after' => 15,
-                'url' => $this->generateUrl('jury_language', ['langId' => $language->getLangid()]),
+                'url' => $this->generateUrl('jury_language', ['langId' => $language->getExternalid()]),
                 'ajax' => true,
             ],
         ];
@@ -224,7 +225,7 @@ public function viewAction(Request $request, SubmissionService $submissionServic
     #[Route(path: '/{langId}/toggle-submit', name: 'jury_language_toggle_submit')]
     public function toggleSubmitAction(Request $request, string $langId): Response
     {
-        $language = $this->em->getRepository(Language::class)->find($langId);
+        $language = $this->em->getRepository(Language::class)->findByExternalId($langId);
         if (!$language) {
             throw new NotFoundHttpException(sprintf('Language with ID %s not found', $langId));
         }
@@ -232,7 +233,7 @@ public function toggleSubmitAction(Request $request, string $langId): Response
         $language->setAllowSubmit($request->request->getBoolean('value'));
         $this->em->flush();
 
-        $this->dj->auditlog('language', $langId, 'set allow submit',
+        $this->dj->auditlog('language', $language->getExternalid(), 'set allow submit',
                                          $request->request->getBoolean('value') ? 'yes' : 'no');
         return $this->redirectToRoute('jury_language', ['langId' => $langId]);
     }
@@ -243,7 +244,7 @@ public function toggleJudgeAction(
         Request $request,
         string $langId
     ): Response {
-        $language = $this->em->getRepository(Language::class)->find($langId);
+        $language = $this->em->getRepository(Language::class)->findByExternalId($langId);
         if (!$language) {
             throw new NotFoundHttpException(sprintf('Language with ID %s not found', $langId));
         }
@@ -253,10 +254,10 @@ public function toggleJudgeAction(
         $this->em->flush();
 
         if ($enabled) {
-            $this->dj->unblockJudgeTasksForLanguage($langId);
+            $this->dj->unblockJudgeTasksForLanguage($language->getLangid());
         }
 
-        $this->dj->auditlog('language', $langId, 'set allow judge',
+        $this->dj->auditlog('language', $language->getExternalid(), 'set allow judge',
                                          $request->request->getBoolean('value') ? 'yes' : 'no');
         return $this->redirectToLocalReferrer(
             $router,
@@ -268,7 +269,7 @@ public function toggleJudgeAction(
     #[Route(path: '/{langId}/toggle-filter-compiler-flags', name: 'jury_language_toggle_filter_compiler_files')]
     public function toggleFilterCompilerFlagsAction(Request $request, string $langId): Response
     {
-        $language = $this->em->getRepository(Language::class)->find($langId);
+        $language = $this->em->getRepository(Language::class)->findByExternalId($langId);
         if (!$language) {
             throw new NotFoundHttpException(sprintf('Language with ID %s not found', $langId));
         }
@@ -277,7 +278,7 @@ public function toggleFilterCompilerFlagsAction(Request $request, string $langId
         $language->setFilterCompilerFiles($enabled);
         $this->em->flush();
 
-        $this->dj->auditlog('language', $langId, 'set filter compiler flags',
+        $this->dj->auditlog('language', $language->getExternalid(), 'set filter compiler flags',
             $request->request->getBoolean('value') ? 'yes' : 'no');
         return $this->redirectToRoute('jury_language', ['langId' => $langId]);
     }
@@ -286,7 +287,7 @@ public function toggleFilterCompilerFlagsAction(Request $request, string $langId
     #[Route(path: '/{langId}/edit', name: 'jury_language_edit')]
     public function editAction(Request $request, string $langId): Response
     {
-        $language = $this->em->getRepository(Language::class)->find($langId);
+        $language = $this->em->getRepository(Language::class)->findByExternalId($langId);
         if (!$language) {
             throw new NotFoundHttpException(sprintf('Language with ID %s not found', $langId));
         }
@@ -302,7 +303,7 @@ public function editAction(Request $request, string $langId): Response
             }
             $this->saveEntity($language, $language->getLangid(), false);
             if ($language->getAllowJudge()) {
-                $this->dj->unblockJudgeTasksForLanguage($langId);
+                $this->dj->unblockJudgeTasksForLanguage($language->getLangid());
             }
             return $this->redirectToRoute('jury_language', ['langId' => $language->getLangid()]);
         }
@@ -317,7 +318,7 @@ public function editAction(Request $request, string $langId): Response
     #[Route(path: '/{langId}/delete', name: 'jury_language_delete')]
     public function deleteAction(Request $request, string $langId): Response
     {
-        $language = $this->em->getRepository(Language::class)->find($langId);
+        $language = $this->em->getRepository(Language::class)->findByExternalId($langId);
         if (!$language) {
             throw new NotFoundHttpException(sprintf('Language with ID %s not found', $langId));
         }
@@ -329,11 +330,11 @@ public function deleteAction(Request $request, string $langId): Response
     #[Route(path: '/{langId}/request-remaining', name: 'jury_language_request_remaining')]
     public function requestRemainingRunsWholeLanguageAction(string $langId): RedirectResponse
     {
-        $language = $this->em->getRepository(Language::class)->find($langId);
+        $language = $this->em->getRepository(Language::class)->findByExternalId($langId);
         if (!$language) {
             throw new NotFoundHttpException(sprintf('Language with ID %s not found', $langId));
         }
-        $contestId = $this->dj->getCurrentContest()->getCid();
+        $contestId = $this->dj->getCurrentContest()->getExternalid();
         $this->judgeRemaining(contestId: $contestId, langId: $langId);
         return $this->redirectToRoute('jury_language', ['langId' => $langId]);
     }
diff --git a/webapp/src/Controller/Jury/ProblemController.php b/webapp/src/Controller/Jury/ProblemController.php
index e10cc3f6be..4b8c33967c 100644
--- a/webapp/src/Controller/Jury/ProblemController.php
+++ b/webapp/src/Controller/Jury/ProblemController.php
@@ -76,10 +76,9 @@ public function indexAction(): Response
             ->getQuery()->getResult();
 
         $table_fields = [
-            'probid' => ['title' => 'ID', 'sort' => true, 'default_sort' => true],
-            'externalid' => ['title' => 'external ID', 'sort' => true],
+            'externalid' => ['title' => 'ID', 'sort' => true],
             'name' => ['title' => 'name', 'sort' => true],
-            'badges' => ['title' => '', 'sort' => false],
+            'badges' => ['title' => '', 'sort' => true],
             'num_contests' => ['title' => '# contests', 'sort' => true],
             'timelimit' => ['title' => 'time limit', 'sort' => true],
             'memlimit' => ['title' => 'memory limit', 'sort' => true],
@@ -88,6 +87,12 @@ public function indexAction(): Response
             'type' => ['title' => 'type', 'sort' => true],
         ];
 
+        if ($this->dj->getCurrentContest() !== null) {
+            $table_fields['badges']['default_sort'] = true;
+        } else {
+            $table_fields['badges']['externalid'] = true;
+        }
+
         $this->addSelectAllCheckbox($table_fields, 'problems');
 
         $contestCountData = $this->em->createQueryBuilder()
@@ -112,7 +117,7 @@ public function indexAction(): Response
             $problemdata    = [];
             $problemactions = [];
 
-            $this->addEntityCheckbox($problemdata, $p, $p->getProbid(), 'problem-checkbox', fn(Problem $problem) => !$problem->isLocked());
+            $this->addEntityCheckbox($problemdata, $p, $p->getExternalid(), 'problem-checkbox', fn(Problem $problem) => !$problem->isLocked());
 
             // Get whatever fields we can from the problem object itself.
             foreach ($table_fields as $k => $v) {
@@ -127,7 +132,7 @@ public function indexAction(): Response
                     'icon' => 'file-' . $p->getProblemstatementType(),
                     'title' => 'view problem statement',
                     'link' => $this->generateUrl('jury_problem_statement', [
-                        'probId' => $p->getProbid(),
+                        'probId' => $p->getExternalid(),
                     ])
                 ];
             } else {
@@ -137,7 +142,7 @@ public function indexAction(): Response
                 'icon' => 'save',
                 'title' => 'export problem as zip-file',
                 'link' => $this->generateUrl('jury_export_problem', [
-                    'problemId' => $p->getProbid(),
+                    'problemId' => $p->getExternalid(),
                 ])
             ];
 
@@ -146,7 +151,7 @@ public function indexAction(): Response
                     'icon' => 'edit',
                     'title' => 'edit this problem',
                     'link' => $this->generateUrl('jury_problem_edit', [
-                        'probId' => $p->getProbid(),
+                        'probId' => $p->getExternalid(),
                     ])
                 ];
 
@@ -161,7 +166,7 @@ public function indexAction(): Response
                     'icon' => 'trash-alt',
                     'title' => 'delete this problem',
                     'link' => $this->generateUrl('jury_problem_delete', [
-                        'probId' => $p->getProbid(),
+                        'probId' => $p->getExternalid(),
                     ]),
                     'ajaxModal' => true,
                 ];
@@ -206,7 +211,10 @@ public function indexAction(): Response
             if ($this->dj->getCurrentContest() !== null) {
                 $badges = array_filter($contestProblems, fn($cp) => $cp->getCid() === $this->dj->getCurrentContest()->getCid());
             }
-            $problemdata['badges'] = ['value' => $badges];
+            $problemdata['badges'] = [
+                'value' => $badges,
+                'sortvalue' => implode(', ', array_map(fn(ContestProblem $problem) => $problem->getShortname(), $badges)),
+            ];
 
             // merge in the rest of the data
             $problemdata = array_merge($problemdata, [
@@ -218,7 +226,7 @@ public function indexAction(): Response
             $data_to_add = [
                 'data' => $problemdata,
                 'actions' => $problemactions,
-                'link' => $this->generateUrl('jury_problem', ['probId' => $p->getProbid()]),
+                'link' => $this->generateUrl('jury_problem', ['probId' => $p->getExternalid()]),
             ];
             if ($badges) {
                 $problems_table_current[] = $data_to_add;
@@ -246,16 +254,13 @@ public function problemsetAction(StatisticsService $stats): Response
             $this->dj->getTwigDataForProblemsAction($stats, teamId: $teamId, forJury: true));
     }
 
-    #[Route(path: '/{probId<\d+>}/samples.zip', name: 'jury_problem_sample_zip')]
-    public function sampleZipAction(int $probId): StreamedResponse
+    #[Route(path: '/{probId}/samples.zip', name: 'jury_problem_sample_zip')]
+    public function sampleZipAction(string $probId): StreamedResponse
     {
         $contest = $this->dj->getCurrentContest();
-        $contestProblem = $this->em->getRepository(ContestProblem::class)->find([
-            'problem' => $probId,
-            'contest' => $contest,
-        ]);
+        $contestProblem = $this->em->getRepository(ContestProblem::class)->findByProblemAndContest($contest, $probId);
         if (!$contestProblem) {
-            throw new NotFoundHttpException(sprintf('Problem p%d not found or not available', $probId));
+            throw new NotFoundHttpException(sprintf('Problem %s not found or not available', $probId));
         }
         return $this->dj->getSamplesZipStreamedResponse($contestProblem);
     }
@@ -264,8 +269,8 @@ public function sampleZipAction(int $probId): StreamedResponse
      * @throws NonUniqueResultException
      */
     #[IsGranted('ROLE_JURY')]
-    #[Route(path: '/{problemId<\d+>}/export', name: 'jury_export_problem')]
-    public function exportAction(int $problemId): StreamedResponse
+    #[Route(path: '/{problemId}/export', name: 'jury_export_problem')]
+    public function exportAction(string $problemId): StreamedResponse
     {
         // This might take a while.
         Utils::extendMaxExecutionTime(300);
@@ -275,7 +280,7 @@ public function exportAction(int $problemId): StreamedResponse
             ->leftJoin('p.contest_problems', 'cp', Join::WITH, 'cp.contest = :contest')
             ->leftJoin('p.problemStatementContent', 'content')
             ->select('p', 'cp', 'content')
-            ->andWhere('p.probid = :problemId')
+            ->andWhere('p.externalid = :problemId')
             ->setParameter('problemId', $problemId)
             ->setParameter('contest', $this->dj->getCurrentContest())
             ->getQuery()
@@ -412,7 +417,7 @@ public function exportAction(int $problemId): StreamedResponse
             // since we can't change the filename to something unique, since
             // that could break e.g. Java sources, even if _we_ support this
             // by default.
-            $directory = sprintf('submissions/%s/s%d/', $problemResult, $solution->getSubmitid());
+            $directory = sprintf('submissions/%s/%s/', $problemResult, $solution->getExternalid());
             /** @var SubmissionFile $source */
             foreach ($solution->getFiles() as $source) {
                 $zip->addFromString($directory . $source->getFilename(), $source->getSourcecode());
@@ -423,7 +428,7 @@ public function exportAction(int $problemId): StreamedResponse
         if ($contestProblem && $contestProblem->getShortname()) {
             $zipFilename = sprintf('%s.zip', $contestProblem->getShortname());
         } else {
-            $zipFilename = sprintf('p%d.zip', $problem->getProbid());
+            $zipFilename = sprintf('%s.zip', $problem->getExternalid());
         }
 
         return Utils::streamZipFile($tempFilename, $zipFilename);
@@ -433,10 +438,10 @@ public function exportAction(int $problemId): StreamedResponse
      * @throws NoResultException
      * @throws NonUniqueResultException
      */
-    #[Route(path: '/{probId<\d+>}', name: 'jury_problem')]
-    public function viewAction(Request $request, SubmissionService $submissionService, int $probId): Response
+    #[Route(path: '/{probId}', name: 'jury_problem')]
+    public function viewAction(Request $request, SubmissionService $submissionService, string $probId): Response
     {
-        $problem = $this->em->getRepository(Problem::class)->find($probId);
+        $problem = $this->em->getRepository(Problem::class)->findByExternalId($probId);
         if (!$problem) {
             throw new NotFoundHttpException(sprintf('Problem with ID %s not found', $probId));
         }
@@ -446,7 +451,7 @@ public function viewAction(Request $request, SubmissionService $submissionServic
             /** @var ContestProblem $contestProblem */
             if ($contestProblem->getContest()->isLocked()) {
                 if (!$request->isXmlHttpRequest()) {
-                    $this->addFlash('warning', 'Cannot edit problem, it belongs to locked contest c' . $contestProblem->getContest()->getCid());
+                    $this->addFlash('warning', 'Cannot edit problem, it belongs to locked contest ' . $contestProblem->getContest()->getExternalid());
                 }
                 $lockedProblem = true;
             }
@@ -498,6 +503,10 @@ public function viewAction(Request $request, SubmissionService $submissionServic
 
         $data = [
             'problem' => $problem,
+            'previousNext' => $this->getPreviousAndNextObjectIds(
+                Problem::class,
+                $problem->getExternalid(),
+            ),
             'problemAttachmentForm' => $problemAttachmentForm->createView(),
             'submissions' => $submissions,
             'submissionCounts' => $submissionCounts,
@@ -511,7 +520,7 @@ public function viewAction(Request $request, SubmissionService $submissionServic
             'lockedProblem' => $lockedProblem,
             'refresh' => [
                 'after' => 15,
-                'url' => $this->generateUrl('jury_problem', ['probId' => $problem->getProbid()]),
+                'url' => $this->generateUrl('jury_problem', ['probId' => $problem->getExternalid()]),
                 'ajax' => true,
             ],
         ];
@@ -525,10 +534,10 @@ public function viewAction(Request $request, SubmissionService $submissionServic
         return $this->render('jury/problem.html.twig', $data);
     }
 
-    #[Route(path: '/{probId<\d+>}/statement', name: 'jury_problem_statement')]
-    public function viewTextAction(int $probId): StreamedResponse
+    #[Route(path: '/{probId}/statement', name: 'jury_problem_statement')]
+    public function viewTextAction(string $probId): StreamedResponse
     {
-        $problem = $this->em->getRepository(Problem::class)->find($probId);
+        $problem = $this->em->getRepository(Problem::class)->findByExternalId($probId);
         if (!$problem) {
             throw new NotFoundHttpException(sprintf('Problem with ID %s not found', $probId));
         }
@@ -536,10 +545,10 @@ public function viewTextAction(int $probId): StreamedResponse
         return $problem->getProblemStatementStreamedResponse();
     }
 
-    #[Route(path: '/{probId<\d+>}/testcases', name: 'jury_problem_testcases')]
-    public function testcasesAction(Request $request, int $probId): Response
+    #[Route(path: '/{probId}/testcases', name: 'jury_problem_testcases')]
+    public function testcasesAction(Request $request, string $probId): Response
     {
-        $problem = $this->em->getRepository(Problem::class)->find($probId);
+        $problem = $this->em->getRepository(Problem::class)->findByExternalId($probId);
         if (!$problem) {
             throw new NotFoundHttpException(sprintf('Problem with ID %s not found', $probId));
         }
@@ -548,7 +557,7 @@ public function testcasesAction(Request $request, int $probId): Response
         foreach ($problem->getContestProblems() as $contestproblem) {
             /** @var ContestProblem $contestproblem */
             if ($contestproblem->getContest()->isLocked()) {
-                $lockedContests[] = 'c' . $contestproblem->getContest()->getCid();
+                $lockedContests[] = $contestproblem->getContest()->getExternalid();
                 break;
             }
         }
@@ -571,7 +580,7 @@ public function testcasesAction(Request $request, int $probId): Response
             if (!empty($lockedContests)) {
                 $this->addFlash('danger', 'Cannot edit problem / testcases, it belongs to locked contest(s) '
                     . join(', ', $lockedContests));
-                return $this->redirectToRoute('jury_problem', ['probId' => $problem->getProbid()]);
+                return $this->redirectToRoute('jury_problem', ['probId' => $problem->getExternalid()]);
             }
             $messages      = [];
             $maxrank       = 0;
@@ -637,7 +646,7 @@ public function testcasesAction(Request $request, int $probId): Response
                             }
                         }
 
-                        $this->dj->auditlog('testcase', $probId, 'updated',
+                        $this->dj->auditlog('testcase', $problem->getExternalid(), 'updated',
                                             sprintf('%s rank %d', $type, $rank));
 
                         $message = sprintf('Updated %s for testcase %d with file %s (%s)',
@@ -739,7 +748,7 @@ public function testcasesAction(Request $request, int $probId): Response
                 }
 
                 $this->em->persist($newTestcase);
-                $this->dj->auditlog('testcase', $probId, 'added', sprintf("rank %d", $maxrank));
+                $this->dj->auditlog('testcase', $problem->getExternalid(), 'added', sprintf("rank %d", $maxrank));
 
                 $inFile  = $request->files->get('add_input');
                 $outFile = $request->files->get('add_output');
@@ -803,10 +812,10 @@ public function testcasesAction(Request $request, int $probId): Response
     }
 
     #[IsGranted('ROLE_ADMIN')]
-    #[Route(path: '/{probId<\d+>}/testcases/{rank<\d+>}/move/{direction<up|down>}', name: 'jury_problem_testcase_move')]
-    public function moveTestcaseAction(int $probId, int $rank, string $direction): Response
+    #[Route(path: '/{probId}/testcases/{rank<\d+>}/move/{direction<up|down>}', name: 'jury_problem_testcase_move')]
+    public function moveTestcaseAction(string $probId, int $rank, string $direction): Response
     {
-        $problem = $this->em->getRepository(Problem::class)->find($probId);
+        $problem = $this->em->getRepository(Problem::class)->findByExternalId($probId);
         if (!$problem) {
             throw new NotFoundHttpException(sprintf('Problem with ID %s not found', $probId));
         }
@@ -815,7 +824,7 @@ public function moveTestcaseAction(int $probId, int $rank, string $direction): R
             /** @var ContestProblem $contestProblem */
             if ($contestProblem->getContest()->isLocked()) {
                 $this->addFlash('danger', 'Cannot edit problem, it belongs to locked contest c' . $contestProblem->getContest()->getCid());
-                return $this->redirectToRoute('jury_problem', ['probId' => $problem->getProbid()]);
+                return $this->redirectToRoute('jury_problem', ['probId' => $problem->getExternalid()]);
             }
         }
 
@@ -866,7 +875,7 @@ public function moveTestcaseAction(int $probId, int $rank, string $direction): R
                 $other->setRank($currentRank);
             });
 
-            $this->dj->auditlog('testcase', $probId, 'switch rank',
+            $this->dj->auditlog('testcase', $problem->getExternalid(), 'switch rank',
                                              sprintf("%d <=> %d", $current->getRank(), $other->getRank()));
         }
 
@@ -876,28 +885,29 @@ public function moveTestcaseAction(int $probId, int $rank, string $direction): R
     /**
      * @throws NonUniqueResultException
      */
-    #[Route(path: '/{probId<\d+>}/testcases/{rank<\d+>}/fetch/{type<input|output|image>}', name: 'jury_problem_testcase_fetch')]
-    public function fetchTestcaseAction(int $probId, int $rank, string $type): Response
+    #[Route(path: '/{probId}/testcases/{rank<\d+>}/fetch/{type<input|output|image>}', name: 'jury_problem_testcase_fetch')]
+    public function fetchTestcaseAction(string $probId, int $rank, string $type): Response
     {
         /** @var Testcase|null $testcase */
         $testcase = $this->em->createQueryBuilder()
             ->from(Testcase::class, 'tc')
             ->join('tc.content', 'tcc')
+            ->join('tc.problem', 'p')
             ->select('tc', 'tcc')
-            ->andWhere('tc.problem = :problem')
+            ->andWhere('p.externalid = :problem')
             ->andWhere('tc.ranknumber = :ranknumber')
             ->setParameter('problem', $probId)
             ->setParameter('ranknumber', $rank)
             ->getQuery()
             ->getOneOrNullResult();
         if (!$testcase) {
-            throw new NotFoundHttpException(sprintf('Testcase with rank %d for problem %d not found', $rank, $probId));
+            throw new NotFoundHttpException(sprintf('Testcase with rank %d for problem %s not found', $rank, $probId));
         }
 
         if ($type === 'image') {
             $extension = $testcase->getImageType();
             $mimetype  = sprintf('image/%s', $extension);
-            $filename  = sprintf('p%d.t%d.%s', $probId, $rank, $extension);
+            $filename  = sprintf('%s.t%d.%s', $probId, $rank, $extension);
         } else {
             $extension = Testcase::EXTENSION_MAPPING[$type];
             $mimetype  = 'text/plain';
@@ -930,10 +940,10 @@ public function fetchTestcaseAction(int $probId, int $rank, string $type): Respo
     }
 
     #[IsGranted('ROLE_ADMIN')]
-    #[Route(path: '/{probId<\d+>}/edit', name: 'jury_problem_edit')]
-    public function editAction(Request $request, int $probId): Response
+    #[Route(path: '/{probId}/edit', name: 'jury_problem_edit')]
+    public function editAction(Request $request, string $probId): Response
     {
-        $problem = $this->em->getRepository(Problem::class)->find($probId);
+        $problem = $this->em->getRepository(Problem::class)->findByExternalId($probId);
         if (!$problem) {
             throw new NotFoundHttpException(sprintf('Problem with ID %s not found', $probId));
         }
@@ -941,8 +951,8 @@ public function editAction(Request $request, int $probId): Response
         foreach ($problem->getContestProblems() as $contestProblem) {
             /** @var ContestProblem $contestProblem */
             if ($contestProblem->getContest()->isLocked()) {
-                $this->addFlash('danger', 'Cannot edit problem, it belongs to locked contest c' . $contestProblem->getContest()->getCid());
-                return $this->redirectToRoute('jury_problem', ['probId' => $problem->getProbid()]);
+                $this->addFlash('danger', 'Cannot edit problem, it belongs to locked contest ' . $contestProblem->getContest()->getExternalid());
+                return $this->redirectToRoute('jury_problem', ['probId' => $problem->getExternalid()]);
             }
         }
 
@@ -952,7 +962,7 @@ public function editAction(Request $request, int $probId): Response
 
         if ($form->isSubmitted() && $form->isValid()) {
             $this->saveEntity($problem, $problem->getProbid(), false);
-            return $this->redirectToRoute('jury_problem', ['probId' => $problem->getProbid()]);
+            return $this->redirectToRoute('jury_problem', ['probId' => $problem->getExternalid()]);
         }
 
         $data       = [];
@@ -981,10 +991,10 @@ public function editAction(Request $request, int $probId): Response
                 if ($this->importProblemService->importZippedProblem(
                     $zip, $clientName, $problem, $contest, $messages
                 )) {
-                    $this->dj->auditlog('problem', $problem->getProbid(), 'upload zip', $clientName);
+                    $this->dj->auditlog('problem', $problem->getExternalid(), 'upload zip', $clientName);
                 } else {
                     $this->postMessages($messages);
-                    return $this->redirectToRoute('jury_problem', ['probId' => $problem->getProbid()]);
+                    return $this->redirectToRoute('jury_problem', ['probId' => $problem->getExternalid()]);
                 }
             } catch (Exception $e) {
                 $messages['danger'][] = $e->getMessage();
@@ -995,7 +1005,7 @@ public function editAction(Request $request, int $probId): Response
             }
             $this->postMessages($messages);
 
-            return $this->redirectToRoute('jury_problem', ['probId' => $problem->getProbid()]);
+            return $this->redirectToRoute('jury_problem', ['probId' => $problem->getExternalid()]);
         }
 
         return $this->render('jury/problem_edit.html.twig', [
@@ -1006,13 +1016,13 @@ public function editAction(Request $request, int $probId): Response
     }
 
     #[IsGranted('ROLE_ADMIN')]
-    #[Route(path: '/delete-multiple', name: 'jury_problem_delete_multiple', methods: ['GET', 'POST'])]
+    #[Route(path: '/delete-multiple', name: 'jury_problem_delete_multiple', methods: ['GET', 'POST'], priority: 1)]
     public function deleteMultipleAction(Request $request): Response
     {
         return $this->deleteMultiple(
             $request,
             Problem::class,
-            'probid',
+            'externalid',
             'jury_problems',
             'No problems could be deleted (they might be locked).',
             fn(Problem $problem) => !$problem->isLocked()
@@ -1020,10 +1030,10 @@ public function deleteMultipleAction(Request $request): Response
     }
 
     #[IsGranted('ROLE_ADMIN')]
-    #[Route(path: '/{probId<\d+>}/delete', name: 'jury_problem_delete')]
-    public function deleteAction(Request $request, int $probId): Response
+    #[Route(path: '/{probId}/delete', name: 'jury_problem_delete')]
+    public function deleteAction(Request $request, string $probId): Response
     {
-        $problem = $this->em->getRepository(Problem::class)->find($probId);
+        $problem = $this->em->getRepository(Problem::class)->findByExternalId($probId);
         if (!$problem) {
             throw new NotFoundHttpException(sprintf('Problem with ID %s not found', $probId));
         }
@@ -1031,7 +1041,7 @@ public function deleteAction(Request $request, int $probId): Response
         foreach ($problem->getContestProblems() as $contestProblem) {
             /** @var ContestProblem $contestProblem */
             if ($contestProblem->getContest()->isLocked()) {
-                $this->addFlash('danger', 'Cannot delete problem, it belongs to locked contest c' . $contestProblem->getContest()->getCid());
+                $this->addFlash('danger', 'Cannot delete problem, it belongs to locked contest ' . $contestProblem->getContest()->getExternalid());
                 return $this->redirectToRoute('jury_problem', ['probId' => $probId]);
             }
         }
@@ -1061,7 +1071,7 @@ public function deleteAttachmentAction(Request $request, int $attachmentId): Res
         }
 
         $problem = $attachment->getProblem();
-        $probId = $problem->getProbid();
+        $probId = $problem->getExternalid();
 
         foreach ($problem->getContestProblems() as $contestProblem) {
             /** @var ContestProblem $contestProblem */
@@ -1086,8 +1096,8 @@ public function deleteTestcaseAction(Request $request, int $testcaseId): Respons
         foreach ($problem->getContestProblems() as $contestProblem) {
             /** @var ContestProblem $contestProblem */
             if ($contestProblem->getContest()->isLocked()) {
-                $this->addFlash('danger', 'Cannot edit problem, it belongs to locked contest c' . $contestProblem->getContest()->getCid());
-                return $this->redirectToRoute('jury_problem', ['probId' => $problem->getProbid()]);
+                $this->addFlash('danger', 'Cannot edit problem, it belongs to locked contest ' . $contestProblem->getContest()->getExternalid());
+                return $this->redirectToRoute('jury_problem', ['probId' => $problem->getExternalid()]);
             }
         }
         $testcase->setDeleted(true);
@@ -1103,12 +1113,12 @@ public function deleteTestcaseAction(Request $request, int $testcaseId): Respons
             }
         }
         $this->em->flush();
-        $this->addFlash('danger', sprintf('Testcase %d removed from problem %s. Consider rejudging the problem.', $testcaseId, $problem->getProbid()));
-        return $this->redirectToRoute('jury_problem_testcases', ['probId' => $problem->getProbid()]);
+        $this->addFlash('danger', sprintf('Testcase %d removed from problem %s. Consider rejudging the problem.', $testcaseId, $problem->getExternalid()));
+        return $this->redirectToRoute('jury_problem_testcases', ['probId' => $problem->getExternalid()]);
     }
 
     #[IsGranted('ROLE_ADMIN')]
-    #[Route(path: '/add', name: 'jury_problem_add')]
+    #[Route(path: '/add', name: 'jury_problem_add', priority: 1)]
     public function addAction(Request $request): Response
     {
         $problem = new Problem();
@@ -1119,7 +1129,7 @@ public function addAction(Request $request): Response
 
         if ($response = $this->processAddFormForExternalIdEntity(
             $form, $problem,
-            fn() => $this->generateUrl('jury_problem', ['probId' => $problem->getProbid()])
+            fn() => $this->generateUrl('jury_problem', ['probId' => $problem->getExternalid()])
         )) {
             return $response;
         }
@@ -1176,14 +1186,14 @@ private function addTestcasesToZip(array $testcases, ZipArchive $zip, bool $isSa
         }
     }
 
-    #[Route(path: '/{probId<\d+>}/request-remaining', name: 'jury_problem_request_remaining')]
+    #[Route(path: '/{probId}/request-remaining', name: 'jury_problem_request_remaining')]
     public function requestRemainingRunsWholeProblemAction(string $probId): RedirectResponse
     {
-        $problem = $this->em->getRepository(Problem::class)->find($probId);
+        $problem = $this->em->getRepository(Problem::class)->findByExternalId($probId);
         if (!$problem) {
             throw new NotFoundHttpException(sprintf('Problem with ID %s not found', $probId));
         }
-        $contestId = $this->dj->getCurrentContest()->getCid();
+        $contestId = $this->dj->getCurrentContest()->getExternalid();
         $this->judgeRemaining(contestId: $contestId, probId: $probId);
         return $this->redirectToRoute('jury_problem', ['probId' => $probId]);
     }
@@ -1196,10 +1206,7 @@ public function toggleSubmitAction(
         string $probId,
         string $type
     ): Response {
-        $contestProblem = $this->em->getRepository(ContestProblem::class)->find([
-            'contest' => $contestId,
-            'problem' => $probId,
-        ]);
+        $contestProblem = $this->em->getRepository(ContestProblem::class)->findByProblemAndContest($contestId, $probId);
         if (!$contestProblem) {
             throw new NotFoundHttpException(sprintf('Problem with ID %s not found for contest %s', $probId, $contestId));
         }
@@ -1220,7 +1227,7 @@ public function toggleSubmitAction(
         }
         $this->em->flush();
 
-        $id = [$contestProblem->getCid(), $contestProblem->getProbid()];
+        $id = [$contestProblem->getExternalId(), $contestProblem->getExternalId()];
         $this->dj->auditlog('contest_problem', implode(', ', $id), $label, $value ? 'yes' : 'no');
         return $this->redirectToLocalReferrer($router, $request, $this->generateUrl('jury_problems'));
     }
diff --git a/webapp/src/Controller/Jury/QueueTaskController.php b/webapp/src/Controller/Jury/QueueTaskController.php
index b7e505df62..0e9c505df7 100644
--- a/webapp/src/Controller/Jury/QueueTaskController.php
+++ b/webapp/src/Controller/Jury/QueueTaskController.php
@@ -79,7 +79,7 @@ public function indexAction(): Response
             $queueTaskData['priority']['value'] = static::PRIORITY_MAP[$queueTaskData['priority']['value']];
 
             // Add some links.
-            $queueTaskData['team.name']['link'] = $this->generateUrl('jury_team', ['teamId' => $queueTask->getTeam()->getTeamid()]);
+            $queueTaskData['team.name']['link'] = $this->generateUrl('jury_team', ['teamId' => $queueTask->getTeam()->getExternalid()]);
             $queueTaskData['judgingid']['link'] = $this->generateUrl('jury_submission_by_judging', ['jid' => $queueTask->getJudging()->getJudgingid()]);
 
             // Format start time.
diff --git a/webapp/src/Controller/Jury/RejudgingController.php b/webapp/src/Controller/Jury/RejudgingController.php
index da05c10a79..9487efe444 100644
--- a/webapp/src/Controller/Jury/RejudgingController.php
+++ b/webapp/src/Controller/Jury/RejudgingController.php
@@ -392,6 +392,12 @@ public function viewAction(
 
         $data = [
             'rejudging' => $rejudging,
+            'previousNext' => $this->getPreviousAndNextObjectIds(
+                Rejudging::class,
+                $rejudging->getRejudgingid(),
+                'rejudgingid',
+                ['e.rejudgingid' => 'ASC'],
+            ),
             'todo' => $todo,
             'done' => $done,
             'verdicts' => $verdicts,
@@ -700,13 +706,13 @@ public function createAction(Request $request): Response
 
         // These are the tables that we can deal with.
         $tablemap = [
-            'contest' => 's.contest',
+            'contest' => 'c.externalid',
             'judgehost' => 'jt.judgehost',
-            'language' => 's.language',
-            'problem' => 's.problem',
-            'submission' => 's.submitid',
-            'team' => 's.team',
-            'user' => 's.user',
+            'language' => 'l.externalid',
+            'problem' => 'p.externalid',
+            'submission' => 's.externalid',
+            'team' => 't.externalid',
+            'user' => 'u.externalid',
             'rejudging' => 'j2.rejudging',
         ];
 
@@ -737,7 +743,11 @@ public function createAction(Request $request): Response
                 ->from(Judging::class, 'j')
                 ->leftJoin('j.submission', 's')
                 ->leftJoin('s.rejudging', 'r')
+                ->leftJoin('s.contest', 'c')
+                ->leftJoin('s.language', 'l')
+                ->leftJoin('s.problem', 'p')
                 ->leftJoin('s.team', 't')
+                ->leftJoin('s.user', 'u')
                 ->leftJoin('j.runs', 'jr')
                 ->leftJoin('jr.judgetask', 'jt')
                 ->select('j', 's', 'r', 't')
@@ -804,10 +814,10 @@ private function generateFlashMessagesForSkippedJudgings(array $skipped): void
         /** @var Judging $judging */
         foreach ($skipped as $judging) {
             $submission = $judging->getSubmission();
-            $submitid = $submission->getSubmitid();
+            $submitid = $submission->getExternalid();
             $rejudgingid = $submission->getRejudging()->getRejudgingid();
             $msg = sprintf(
-                'Skipping submission s%d since it is ' .
+                'Skipping submission %s since it is ' .
                 'already part of rejudging r%d.',
                 $submitid,
                 $rejudgingid
@@ -837,7 +847,7 @@ private function getStats(Rejudging $rejudging): array
             ->leftJoin('j.rejudging', 'r')
             ->leftJoin('j.submission', 's')
             ->leftJoin('jt.judgehost', 'jh')
-            ->select('r.rejudgingid, j.judgingid', 's.submitid', 'jh.hostname', 'j.result',
+            ->select('r.rejudgingid, j.judgingid', 's.externalid as submitid', 'jh.hostname', 'j.result',
                 'AVG(jr.runtime) AS runtime_avg', 'COUNT(jr.runtime) AS ntestcases',
                 '(j.endtime - j.starttime) AS duration'
             )
@@ -896,7 +906,8 @@ private function getStats(Rejudging $rejudging): array
                 ->select('t.ranknumber', 'MAX(jr.runtime) - MIN(jr.runtime) AS spread')
                 ->leftJoin('jr.judging', 'j')
                 ->leftJoin('jr.testcase', 't')
-                ->andWhere('j.submission = :submitid')
+                ->leftJoin('j.submission', 's')
+                ->andWhere('s.externalid = :submitid')
                 ->setParameter('submitid', $submitid)
                 ->groupBy('jr.testcase')
                 ->getQuery()
diff --git a/webapp/src/Controller/Jury/SubmissionController.php b/webapp/src/Controller/Jury/SubmissionController.php
index 3097765723..d3a3cdea74 100644
--- a/webapp/src/Controller/Jury/SubmissionController.php
+++ b/webapp/src/Controller/Jury/SubmissionController.php
@@ -119,25 +119,25 @@ public function indexAction(
 
         $contests = $this->dj->getCurrentContests();
         if ($contest = $this->dj->getCurrentContest()) {
-            $contests = [$contest->getCid() => $contest];
+            $contests = [$contest->getExternalid() => $contest];
         }
 
         // Load preselected filters
         $filtersFromCookie = Utils::jsonDecode((string)$this->dj->getCookie('domjudge_submissionsfilter') ?: '[]');
 
         $formAssociationFields = [
-            'problem_id' => [Problem::class, 'probid'],
-            'language_id' => [Language::class, 'langid'],
-            'team_id' => [Team::class, 'teamid'],
-            'category_id' => [TeamCategory::class, 'categoryid'],
-            'affiliation_id' => [TeamAffiliation::class, 'affilid'],
+            'problem_id' => Problem::class,
+            'language_id' => Language::class,
+            'team_id' => Team::class,
+            'category_id' => TeamCategory::class,
+            'affiliation_id' => TeamAffiliation::class,
         ];
 
         // Build the filter form.
         $filtersForForm = ['result' => $filtersFromCookie['result'] ?? []];
         $hasFilters = !empty($filtersForForm['result']);
-        foreach ($formAssociationFields as $field => [$entityClass, $idField]) {
-            $filtersForForm[$field] = $this->em->getRepository($entityClass)->findBy([$idField => $filtersFromCookie[$field] ?? []]);
+        foreach ($formAssociationFields as $field => $entityClass) {
+            $filtersForForm[$field] = $this->em->getRepository($entityClass)->findBy(['externalid' => $filtersFromCookie[$field] ?? []]);
             $hasFilters = $hasFilters || !empty($filtersForForm[$field]);
         }
         $appliedFilters = $filtersForForm;
@@ -149,13 +149,13 @@ public function indexAction(
         if ($form->isSubmitted() && $form->isValid()) {
             $filtersForCookie = ['result' => $form->get('result')->getData()];
             $hasFilters = !empty($filtersForCookie['result']);
-            foreach ($formAssociationFields as $field => [$entityClass, $idField]) {
-                $method = 'get' . ucfirst($idField);
-                $filtersForCookie[$field] = array_map(fn($entity) => $entity->$method(), $form->get($field)->getData());
+            $appliedFilters = [];
+            foreach ($formAssociationFields as $field => $entityClass) {
+                $filtersForCookie[$field] = array_map(fn($entity) => $entity->getExternalid(), $form->get($field)->getData());
                 $hasFilters = $hasFilters || !empty($filtersForCookie[$field]);
+                $appliedFilters[$field] = $form->get($field)->getData();
             }
             $response = $this->dj->setCookie('domjudge_submissionsfilter', Utils::jsonEncode($filtersForCookie), response: $response);
-            $appliedFilters = $filtersForCookie;
         }
 
         if (!empty($appliedFilters['result'])) {
@@ -188,10 +188,10 @@ public function indexAction(
         $disabledLangs = [];
         foreach ($submissions as $submission) {
             if (!$submission->getContestProblem()->getAllowJudge()) {
-                $disabledProblems[$submission->getProblemId()] = $submission->getProblem()->getName();
+                $disabledProblems[$submission->getExternalid()] = $submission->getProblem()->getName();
             }
             if (!$submission->getLanguage()->getAllowJudge()) {
-                $disabledLangs[$submission->getLanguage()->getLangid()] = $submission->getLanguage()->getName();
+                $disabledLangs[$submission->getLanguage()->getExternalid()] = $submission->getLanguage()->getName();
             }
         }
 
@@ -225,10 +225,10 @@ public function indexAction(
     /**
      * @throws NonUniqueResultException
      */
-    #[Route(path: '/{submitId<\d+>}', name: 'jury_submission')]
+    #[Route(path: '/{submitId}', name: 'jury_submission')]
     public function viewAction(
         Request $request,
-        int $submitId,
+        string $submitId,
         #[MapQueryParameter(name: 'jid')]
         ?int $judgingId = null,
         #[MapQueryParameter(name: 'rejudgingid')]
@@ -240,11 +240,17 @@ public function viewAction(
 
         // If judging ID is not set but rejudging ID is, try to deduce the judging ID from the database.
         if (!isset($judgingId) && isset($rejudgingId)) {
-            $judging = $this->em->getRepository(Judging::class)
-                ->findOneBy([
-                                'submission' => $submitId,
-                                'rejudging' => $rejudgingId
-                            ]);
+            /** @var Judging|null $judging */
+            $judging = $this->em->createQueryBuilder()
+                ->from(Judging::class, 'j')
+                ->select('j')
+                ->innerJoin('j.submission', 's')
+                ->andWhere('j.rejudging = :rejudgingId')
+                ->andWhere('s.externalid = :submitId')
+                ->setParameter('rejudgingId', $rejudgingId)
+                ->setParameter('submitId', $submitId)
+                ->getQuery()
+                ->getOneOrNullResult();
             if ($judging) {
                 $judgingId = $judging->getJudgingid();
             }
@@ -261,13 +267,13 @@ public function viewAction(
             ->leftJoin('s.external_judgements', 'ej', Join::WITH, 'ej.valid = 1')
             ->leftJoin('s.contest_problem', 'cp')
             ->select('s', 't', 'p', 'l', 'c', 'f', 'cp', 'ej')
-            ->andWhere('s.submitid = :submitid')
+            ->andWhere('s.externalid = :submitid')
             ->setParameter('submitid', $submitId)
             ->getQuery()
             ->getOneOrNullResult();
 
         if (!$submission) {
-            throw new NotFoundHttpException(sprintf('No submission found with ID %d', $submitId));
+            throw new NotFoundHttpException(sprintf('No submission found with ID %s', $submitId));
         }
 
         $judgingData = $this->em->createQueryBuilder()
@@ -562,6 +568,12 @@ public function viewAction(
 
         $twigData = [
             'submission' => $submission,
+            'previousNext' => $this->getPreviousAndNextObjectIds(
+                Submission::class,
+                $submission->getExternalid(),
+                orderBy: ['e.submittime' => 'ASC', 'e.submitid' => 'ASC'],
+                filterOnContest: true,
+            ),
             'lastSubmission' => $lastSubmission,
             'judgings' => $judgings,
             'maxRunTimes' => $maxRunTimes,
@@ -590,7 +602,7 @@ public function viewAction(
             // Automatically refresh page while we wait for judging data.
             $twigData['refresh'] = [
                 'after' => 15,
-                'url' => $this->generateUrl('jury_submission', ['submitId' => $submission->getSubmitid()]),
+                'url' => $this->generateUrl('jury_submission', ['submitId' => $submission->getExternalid()]),
             ];
         } else {
             $contestProblem = $submission->getContestProblem();
@@ -681,7 +693,7 @@ public function requestFullDebug(Request $request, Judging $jid): RedirectRespon
             $this->em->flush();
         }
         return $this->redirectToLocalReferrer($this->router, $request, $this->generateUrl('jury_submission', [
-            'submitId' => $jid->getSubmission()->getSubmitid(),
+            'submitId' => $jid->getSubmission()->getExternalid(),
             'jid' => $jid->getJudgingid(),
         ]));
     }
@@ -715,7 +727,7 @@ public function requestOutput(Request $request, Judging $jid, JudgingRun $jrid):
         $this->em->persist($judgeTask);
         $this->em->flush();
         return $this->redirectToLocalReferrer($this->router, $request, $this->generateUrl('jury_submission', [
-            'submitId' => $jid->getSubmission()->getSubmitid(),
+            'submitId' => $jid->getSubmission()->getExternalid(),
             'jid' => $jid->getJudgingid(),
         ]));
     }
@@ -724,7 +736,7 @@ public function requestOutput(Request $request, Judging $jid, JudgingRun $jrid):
     public function viewForJudgingAction(Judging $jid): RedirectResponse
     {
         return $this->redirectToRoute('jury_submission', [
-            'submitId' => $jid->getSubmission()->getSubmitid(),
+            'submitId' => $jid->getSubmission()->getExternalid(),
             'jid' => $jid->getJudgingid(),
         ]);
     }
@@ -733,7 +745,7 @@ public function viewForJudgingAction(Judging $jid): RedirectResponse
     public function viewForExternalJudgementAction(ExternalJudgement $externalJudgement): RedirectResponse
     {
         return $this->redirectToRoute('jury_submission', [
-            'submitId' => $externalJudgement->getSubmission()->getSubmitid(),
+            'submitId' => $externalJudgement->getSubmission()->getExternalid(),
         ]);
     }
 
@@ -756,35 +768,18 @@ public function viewForContestExternalIdAction(string $externalContestId, string
         }
 
         return $this->redirectToRoute('jury_submission', [
-            'submitId' => $submission->getSubmitid(),
-        ]);
-    }
-
-    #[Route(path: '/by-external-id/{externalId}', name: 'jury_submission_by_external_id')]
-    public function viewForExternalIdAction(string $externalId): RedirectResponse
-    {
-        if (!$this->dj->getCurrentContest()) {
-            throw new BadRequestHttpException("Cannot determine submission from external ID without selecting a contest.");
-        }
-
-        $submission = $this->em->getRepository(Submission::class)
-            ->findOneBy([
-                            'contest' => $this->dj->getCurrentContest(),
-                            'externalid' => $externalId
-                        ]);
-
-        if (!$submission) {
-            throw new NotFoundHttpException(sprintf('No submission found with external ID %s', $externalId));
-        }
-
-        return $this->redirectToRoute('jury_submission', [
-            'submitId' => $submission->getSubmitid(),
+            'submitId' => $submission->getExternalid(),
         ]);
     }
 
     #[Route(path: '/{submission}/runs/{contest}/{run}/team-output', name: 'jury_submission_team_output')]
-    public function teamOutputAction(Submission $submission, Contest $contest, JudgingRun $run): StreamedResponse
-    {
+    public function teamOutputAction(
+        #[MapEntity(mapping: ['submission' => 'externalid'])]
+        Submission $submission,
+        #[MapEntity(mapping: ['contest' => 'externalid'])]
+        Contest $contest,
+        JudgingRun $run,
+    ): StreamedResponse {
         if ($run->getJudging()->getSubmission()->getSubmitid() !== $submission->getSubmitid() || $submission->getContest()->getCid() !== $contest->getCid()) {
             throw new BadRequestHttpException('Integrity problem while fetching team output.');
         }
@@ -792,9 +787,9 @@ public function teamOutputAction(Submission $submission, Contest $contest, Judgi
             throw new NotFoundHttpException('No team output available (yet).');
         }
 
-        $filename = sprintf('p%d.t%d.%s.run%d.team%d.out', $submission->getProblem()->getProbid(), $run->getTestcase()->getRank(),
+        $filename = sprintf('%s.t%d.%s.run%d.%s.out', $submission->getProblem()->getExternalid(), $run->getTestcase()->getRank(),
                             $submission->getContestProblem()->getShortname(), $run->getRunid(),
-                            $submission->getTeam()->getTeamid());
+                            $submission->getTeam()->getExternalid());
 
         $outputRun = $run->getOutput()->getOutputRun();
         return Utils::streamAsBinaryFile($outputRun, $filename);
@@ -809,6 +804,7 @@ private function allowEdit(): bool {
      */
     #[Route(path: '/{submission}/source', name: 'jury_submission_source')]
     public function sourceAction(
+        #[MapEntity(mapping: ['submission' => 'externalid'])]
         Submission $submission,
         #[MapQueryParameter]
         ?int $fetch = null
@@ -840,7 +836,7 @@ public function sourceAction(
         }
 
         /** @var array{
-         *      submitid: int,
+         *      submitid: string,
          *      tag?: string
          * } otherSubmissions
          */
@@ -848,7 +844,7 @@ public function sourceAction(
         $originalSubmission = $submission->getOriginalSubmission();
         if ($originalSubmission) {
             $otherSubmissions[] = [
-                'submitid' => $originalSubmission->getSubmitid(),
+                'submitid' => $originalSubmission->getExternalid(),
                 'tag'      => 'original',
             ];
             /** @var Submission $oldSubmission */
@@ -888,20 +884,21 @@ public function sourceAction(
         }
         if ($oldSubmission !== null) {
             $otherSubmissions[] = [
-                'submitid' => $oldSubmission->getSubmitid(),
+                'submitid' => $oldSubmission->getExternalid(),
                 'tag'      => 'previous',
             ];
         }
 
         $files_query = array_map(fn($s) => $s['submitid'], $otherSubmissions);
-        $files_query[] = $submission->getSubmitid();
+        $files_query[] = $submission->getExternalid();
         /** @var SubmissionFile[] $oldFiles */
         $oldFiles = $this->em->createQueryBuilder()
             ->from(SubmissionFile::class, 'file')
             ->select('file')
-            ->andWhere('file.submission in (:submissions)')
+            ->join('file.submission', 's')
+            ->andWhere('s.externalid in (:submissions)')
             ->setParameter('submissions', $files_query)
-            ->orderBy('file.submission, file.ranknumber')
+            ->orderBy('s.externalid, file.ranknumber')
             ->getQuery()
             ->getResult();
 
@@ -915,7 +912,7 @@ public function sourceAction(
         /** @var array<int, (string|false)> $renames */
         $renames = [];
         foreach ($oldFiles as $f) {
-            $submitId = $f->getSubmission()->getSubmitid();
+            $submitId = $f->getSubmission()->getExternalid();
             $files[$f->getFilename()] ??= [];
             $files[$f->getFilename()][$submitId] = [
                 'rank' => $f->getRank(),
@@ -928,7 +925,7 @@ public function sourceAction(
         }
 
         // Handle file renaming for a single-file submission.
-        $renamedTo = $renames[$submission->getSubmitid()];
+        $renamedTo = $renames[$submission->getExternalid()];
         if ($renamedTo !== false) {
             foreach ($renames as $submitId => $filename) {
                 if ($filename !== false && $filename !== $renamedTo) {
@@ -954,13 +951,18 @@ public function sourceAction(
     }
 
     #[Route(path: '/{submission}/edit-source', name: 'jury_submission_edit_source')]
-    public function editSourceAction(Request $request, Submission $submission, #[MapQueryParameter] ?int $rank = null): Response
-    {
+    public function editSourceAction(
+        Request $request,
+        #[MapEntity(mapping: ['submission' => 'externalid'])]
+        Submission $submission,
+        #[MapQueryParameter]
+        ?int $rank = null
+    ): Response {
         if (!$this->allowEdit()) {
             $this->addFlash('danger', 'You cannot re-submit code without being a team.');
             return $this->redirectToLocalReferrer($this->router, $request, $this->generateUrl(
                 'jury_submission',
-                ['submitId' => $submission->getSubmitid()]
+                ['submitId' => $submission->getExternalid()]
             ));
         }
 
@@ -988,6 +990,7 @@ public function editSourceAction(Request $request, Submission $submission, #[Map
             ->add('problem', EntityType::class, [
                 'class' => Problem::class,
                 'choice_label' => 'name',
+                'choice_value' => 'externalid',
                 'query_builder' => fn(EntityRepository $er) => $er->createQueryBuilder('p')
                     ->join('p.contest_problems', 'cp')
                     ->andWhere('cp.allowSubmit = 1')
@@ -998,6 +1001,7 @@ public function editSourceAction(Request $request, Submission $submission, #[Map
             ->add('language', EntityType::class, [
                 'class' => Language::class,
                 'choice_label' => 'name',
+                'choice_value' => 'externalid',
                 'query_builder' => fn(EntityRepository $er) => $er->createQueryBuilder('lang')
                     ->andWhere('lang.allowSubmit = 1')
                     ->orderBy('lang.name')
@@ -1058,10 +1062,10 @@ public function editSourceAction(Request $request, Submission $submission, #[Map
 
             if (!$submittedSubmission) {
                 $this->addFlash('danger', $message);
-                return $this->redirectToRoute('jury_submission', ['submitId' => $submission->getSubmitid()]);
+                return $this->redirectToRoute('jury_submission', ['submitId' => $submission->getExternalid()]);
             }
 
-            return $this->redirectToRoute('jury_submission', ['submitId' => $submittedSubmission->getSubmitid()]);
+            return $this->redirectToRoute('jury_submission', ['submitId' => $submittedSubmission->getExternalid()]);
         }
 
         $twigData = [
@@ -1098,14 +1102,14 @@ public function requestRemainingRuns(Request $request, int $judgingId): Redirect
      * @throws DBALException
      */
     #[IsGranted('ROLE_ADMIN')]
-    #[Route(path: '/{submitId<\d+>}/update-status', name: 'jury_submission_update_status', methods: ['POST'])]
+    #[Route(path: '/{submitId}/update-status', name: 'jury_submission_update_status', methods: ['POST'])]
     public function updateStatusAction(
         EventLogService $eventLogService,
         ScoreboardService $scoreboardService,
         Request $request,
-        int $submitId
+        string $submitId
     ): RedirectResponse {
-        $submission = $this->em->getRepository(Submission::class)->find($submitId);
+        $submission = $this->em->getRepository(Submission::class)->findByExternalId($submitId);
         $valid      = $request->request->getBoolean('valid');
         $submission->setValid($valid);
         $this->em->flush();
@@ -1118,7 +1122,7 @@ public function updateStatusAction(
         // FIXME: We should also delete/recreate any dependent judging(runs).
         $eventLogService->log('submission', $submission->getSubmitid(), ($valid ? 'create' : 'delete'),
                               $submission->getContest()->getCid(), null, null, $valid);
-        $this->dj->auditlog('submission', $submission->getSubmitid(),
+        $this->dj->auditlog('submission', $submission->getExternalid(),
                                          'marked ' . ($valid ? 'valid' : 'invalid'));
         $contest = $this->em->getRepository(Contest::class)->find($contestId);
         $team    = $this->em->getRepository(Team::class)->find($teamId);
@@ -1126,7 +1130,7 @@ public function updateStatusAction(
         $scoreboardService->calculateScoreRow($contest, $team, $problem);
 
         return $this->redirectToLocalReferrer($this->router, $request,
-            $this->generateUrl('jury_submission', ['submitId' => $submission->getSubmitid()])
+            $this->generateUrl('jury_submission', ['submitId' => $submission->getExternalid()])
         );
     }
 
@@ -1155,7 +1159,7 @@ public function verifyAction(
                 ->setVerifyComment($comment);
 
             $this->em->flush();
-            $this->dj->auditlog('judging', $judging->getJudgingid(),
+            $this->dj->auditlog('judging', (string)$judging->getJudgingid(),
                                              $verified ? 'set verified' : 'set unverified');
 
             if ((bool)$this->config->get('verification_required')) {
@@ -1206,7 +1210,6 @@ public function verifyAction(
 
     #[Route(path: '/shadow-difference/{extjudgementid<\d+>}/verify', name: 'jury_shadow_difference_verify', methods: ['POST'])]
     public function verifyShadowDifferenceAction(
-        EventLogService $eventLogService,
         Request $request,
         int $extjudgementid
     ): RedirectResponse {
@@ -1221,7 +1224,7 @@ public function verifyShadowDifferenceAction(
                 ->setVerifyComment($comment);
 
             $this->em->flush();
-            $this->dj->auditlog('external_judgement', $judgement->getExtjudgementid(),
+            $this->dj->auditlog('external_judgement', (string)$judgement->getExtjudgementid(),
                 $verified ? 'set verified' : 'set unverified');
         });
 
@@ -1267,10 +1270,10 @@ protected function processClaim(
                     $auditLogType = 'judging';
                     $auditLogId = $judging->getJudgingid();
                 }
-                $this->dj->auditlog($auditLogType, $auditLogId, $action . 'ed');
+                $this->dj->auditlog($auditLogType, (string)$auditLogId, $action . 'ed');
 
                 if ($action === 'claim') {
-                    return $this->redirectToRoute('jury_submission', ['submitId' => $judging->getSubmission()->getSubmitid()]);
+                    return $this->redirectToRoute('jury_submission', ['submitId' => $judging->getSubmission()->getExternalid()]);
                 } else {
                     return $this->redirectToLocalReferrer($this->router, $request,
                         $this->generateUrl('jury_submissions')
@@ -1282,7 +1285,7 @@ protected function processClaim(
         return null;
     }
 
-    #[Route(path: '/{submitId<\d+>}/create-tasks', name: 'jury_submission_create_tasks')]
+    #[Route(path: '/{submitId}/create-tasks', name: 'jury_submission_create_tasks')]
     public function createJudgeTasks(string $submitId): RedirectResponse
     {
         $this->dj->unblockJudgeTasksForSubmission($submitId);
diff --git a/webapp/src/Controller/Jury/TeamAffiliationController.php b/webapp/src/Controller/Jury/TeamAffiliationController.php
index ef0ab44ee5..9dd4c9183b 100644
--- a/webapp/src/Controller/Jury/TeamAffiliationController.php
+++ b/webapp/src/Controller/Jury/TeamAffiliationController.php
@@ -37,10 +37,7 @@ public function __construct(
     }
 
     #[Route(path: '', name: 'jury_team_affiliations')]
-    public function indexAction(
-        #[Autowire('%kernel.project_dir%')]
-        string $projectDir
-    ): Response {
+    public function indexAction(): Response {
         $em               = $this->em;
         $teamAffiliations = $em->createQueryBuilder()
             ->select('a', 'COUNT(t.teamid) AS num_teams')
@@ -53,8 +50,7 @@ public function indexAction(
         $showFlags = $this->config->get('show_flags');
 
         $table_fields = [
-            'affilid' => ['title' => 'ID', 'sort' => true],
-            'externalid' => ['title' => 'external ID', 'sort' => true],
+            'externalid' => ['title' => 'ID', 'sort' => true],
             'icpcid' => ['title' => 'ICPC ID', 'sort' => true],
             'shortname' => ['title' => 'shortname', 'sort' => true],
             'name' => ['title' => 'name', 'sort' => true, 'default_sort' => true],
@@ -77,7 +73,7 @@ public function indexAction(
             $affiliationdata    = [];
             $affiliationactions = [];
 
-            $this->addEntityCheckbox($affiliationdata, $teamAffiliation, $teamAffiliation->getAffilid(), 'affiliation-checkbox');
+            $this->addEntityCheckbox($affiliationdata, $teamAffiliation, $teamAffiliation->getExternalid(), 'affiliation-checkbox');
 
             // Get whatever fields we can from the affiliation object itself.
             foreach ($table_fields as $k => $v) {
@@ -91,14 +87,14 @@ public function indexAction(
                     'icon' => 'edit',
                     'title' => 'edit this affiliation',
                     'link' => $this->generateUrl('jury_team_affiliation_edit', [
-                        'affilId' => $teamAffiliation->getAffilid(),
+                        'affilId' => $teamAffiliation->getExternalid(),
                     ])
                 ];
                 $affiliationactions[] = [
                     'icon' => 'trash-alt',
                     'title' => 'delete this affiliation',
                     'link' => $this->generateUrl('jury_team_affiliation_delete', [
-                        'affilId' => $teamAffiliation->getAffilid(),
+                        'affilId' => $teamAffiliation->getExternalid(),
                     ]),
                     'ajaxModal' => true,
                 ];
@@ -114,14 +110,14 @@ public function indexAction(
             }
 
             $affiliationdata['affiliation_logo'] = [
-                'value' => $teamAffiliation->getExternalid() ?? $teamAffiliation->getAffilid(),
+                'value' => $teamAffiliation->getExternalid(),
                 'title' => $teamAffiliation->getShortname(),
             ];
 
             $team_affiliations_table[] = [
                 'data' => $affiliationdata,
                 'actions' => $affiliationactions,
-                'link' => $this->generateUrl('jury_team_affiliation', ['affilId' => $teamAffiliation->getAffilid()]),
+                'link' => $this->generateUrl('jury_team_affiliation', ['affilId' => $teamAffiliation->getExternalid()]),
             ];
         }
 
@@ -131,20 +127,24 @@ public function indexAction(
         ]);
     }
 
-    #[Route(path: '/{affilId<\d+>}', name: 'jury_team_affiliation')]
-    public function viewAction(Request $request, ScoreboardService $scoreboardService, int $affilId): Response
+    #[Route(path: '/{affilId}', name: 'jury_team_affiliation')]
+    public function viewAction(Request $request, ScoreboardService $scoreboardService, string $affilId): Response
     {
-        $teamAffiliation = $this->em->getRepository(TeamAffiliation::class)->find($affilId);
+        $teamAffiliation = $this->em->getRepository(TeamAffiliation::class)->findByExternalId($affilId);
         if (!$teamAffiliation) {
             throw new NotFoundHttpException(sprintf('Team affiliation with ID %s not found', $affilId));
         }
 
         $data = [
             'teamAffiliation' => $teamAffiliation,
+            'previousNext' => $this->getPreviousAndNextObjectIds(
+                TeamAffiliation::class,
+                $teamAffiliation->getExternalid(),
+            ),
             'showFlags' => $this->config->get('show_flags'),
             'refresh' => [
                 'after' => 30,
-                'url' => $this->generateUrl('jury_team_affiliation', ['affilId' => $teamAffiliation->getAffilid()]),
+                'url' => $this->generateUrl('jury_team_affiliation', ['affilId' => $teamAffiliation->getExternalid()]),
                 'ajax' => true,
             ],
             'maxWidth' => $this->config->get('team_column_width'),
@@ -171,10 +171,10 @@ public function viewAction(Request $request, ScoreboardService $scoreboardServic
     }
 
     #[IsGranted('ROLE_ADMIN')]
-    #[Route(path: '/{affilId<\d+>}/edit', name: 'jury_team_affiliation_edit')]
-    public function editAction(Request $request, int $affilId): Response
+    #[Route(path: '/{affilId}/edit', name: 'jury_team_affiliation_edit')]
+    public function editAction(Request $request, string $affilId): Response
     {
-        $teamAffiliation = $this->em->getRepository(TeamAffiliation::class)->find($affilId);
+        $teamAffiliation = $this->em->getRepository(TeamAffiliation::class)->findByExternalId($affilId);
         if (!$teamAffiliation) {
             throw new NotFoundHttpException(sprintf('Team affiliation with ID %s not found', $affilId));
         }
@@ -186,7 +186,7 @@ public function editAction(Request $request, int $affilId): Response
         if ($form->isSubmitted() && $form->isValid()) {
             $this->assetUpdater->updateAssets($teamAffiliation);
             $this->saveEntity($teamAffiliation, $teamAffiliation->getAffilid(), false);
-            return $this->redirectToRoute('jury_team_affiliation', ['affilId' => $teamAffiliation->getAffilid()]);
+            return $this->redirectToRoute('jury_team_affiliation', ['affilId' => $teamAffiliation->getExternalid()]);
         }
 
         return $this->render('jury/team_affiliation_edit.html.twig', [
@@ -196,10 +196,10 @@ public function editAction(Request $request, int $affilId): Response
     }
 
     #[IsGranted('ROLE_ADMIN')]
-    #[Route(path: '/{affilId<\d+>}/delete', name: 'jury_team_affiliation_delete')]
-    public function deleteAction(Request $request, int $affilId): Response
+    #[Route(path: '/{affilId}/delete', name: 'jury_team_affiliation_delete')]
+    public function deleteAction(Request $request, string $affilId): Response
     {
-        $teamAffiliation = $this->em->getRepository(TeamAffiliation::class)->find($affilId);
+        $teamAffiliation = $this->em->getRepository(TeamAffiliation::class)->findByExternalId($affilId);
         if (!$teamAffiliation) {
             throw new NotFoundHttpException(sprintf('Team affiliation with ID %s not found', $affilId));
         }
@@ -208,20 +208,20 @@ public function deleteAction(Request $request, int $affilId): Response
     }
 
     #[IsGranted('ROLE_ADMIN')]
-    #[Route(path: '/delete-multiple', name: 'jury_team_affiliation_delete_multiple', methods: ['GET', 'POST'])]
+    #[Route(path: '/delete-multiple', name: 'jury_team_affiliation_delete_multiple', methods: ['GET', 'POST'], priority: 1)]
     public function deleteMultipleAction(Request $request): Response
     {
         return $this->deleteMultiple(
             $request,
             TeamAffiliation::class,
-            'affilid',
+            'externalid',
             'jury_team_affiliations',
             'No affiliations could be deleted.'
         );
     }
 
     #[IsGranted('ROLE_ADMIN')]
-    #[Route(path: '/add', name: 'jury_team_affiliation_add')]
+    #[Route(path: '/add', name: 'jury_team_affiliation_add', priority: 1)]
     public function addAction(Request $request): Response
     {
         $teamAffiliation = new TeamAffiliation();
@@ -232,7 +232,7 @@ public function addAction(Request $request): Response
 
         if ($response = $this->processAddFormForExternalIdEntity(
             $form, $teamAffiliation,
-            fn() => $this->generateUrl('jury_team_affiliation', ['affilId' => $teamAffiliation->getAffilid()]),
+            fn() => $this->generateUrl('jury_team_affiliation', ['affilId' => $teamAffiliation->getExternalid()]),
             function () use ($teamAffiliation) {
                 $this->em->persist($teamAffiliation);
                 $this->assetUpdater->updateAssets($teamAffiliation);
diff --git a/webapp/src/Controller/Jury/TeamCategoryController.php b/webapp/src/Controller/Jury/TeamCategoryController.php
index 19f845c94f..b3f7cca5d4 100644
--- a/webapp/src/Controller/Jury/TeamCategoryController.php
+++ b/webapp/src/Controller/Jury/TeamCategoryController.php
@@ -56,8 +56,7 @@ public function indexAction(): Response
             ->groupBy('c.categoryid')
             ->getQuery()->getResult();
         $table_fields   = [
-            'categoryid' => ['title' => 'ID', 'sort' => true],
-            'externalid' => ['title' => 'external ID', 'sort' => true],
+            'externalid' => ['title' => 'ID', 'sort' => true],
             'icpcid' => ['title' => 'ICPC ID', 'sort' => true],
             'sortorder' => ['title' => 'sort', 'sort' => true, 'default_sort' => true],
             'name' => ['title' => 'name', 'sort' => true],
@@ -76,7 +75,7 @@ public function indexAction(): Response
             $categorydata    = [];
             $categoryactions = [];
 
-            $this->addEntityCheckbox($categorydata, $teamCategory, $teamCategory->getCategoryid(), 'category-checkbox');
+            $this->addEntityCheckbox($categorydata, $teamCategory, $teamCategory->getExternalid(), 'category-checkbox');
 
             // Get whatever fields we can from the category object itself.
             foreach ($table_fields as $k => $v) {
@@ -90,14 +89,14 @@ public function indexAction(): Response
                     'icon' => 'edit',
                     'title' => 'edit this category',
                     'link' => $this->generateUrl('jury_team_category_edit', [
-                        'categoryId' => $teamCategory->getCategoryid(),
+                        'categoryId' => $teamCategory->getExternalid(),
                     ])
                 ];
                 $categoryactions[] = [
                     'icon' => 'trash-alt',
                     'title' => 'delete this category',
                     'link' => $this->generateUrl('jury_team_category_delete', [
-                        'categoryId' => $teamCategory->getCategoryid(),
+                        'categoryId' => $teamCategory->getExternalid(),
                     ]),
                     'ajaxModal' => true,
                 ];
@@ -110,7 +109,7 @@ public function indexAction(): Response
             $team_categories_table[] = [
                 'data' => $categorydata,
                 'actions' => $categoryactions,
-                'link' => $this->generateUrl('jury_team_category', ['categoryId' => $teamCategory->getCategoryid()]),
+                'link' => $this->generateUrl('jury_team_category', ['categoryId' => $teamCategory->getExternalid()]),
                 'style' => $teamCategory->getColor() ? sprintf('background-color: %s;', $teamCategory->getColor()) : '',
             ];
         }
@@ -124,10 +123,10 @@ public function indexAction(): Response
      * @throws NoResultException
      * @throws NonUniqueResultException
      */
-    #[Route(path: '/{categoryId<\d+>}', name: 'jury_team_category')]
-    public function viewAction(Request $request, SubmissionService $submissionService, int $categoryId): Response
+    #[Route(path: '/{categoryId}', name: 'jury_team_category')]
+    public function viewAction(Request $request, SubmissionService $submissionService, string $categoryId): Response
     {
-        $teamCategory = $this->em->getRepository(TeamCategory::class)->find($categoryId);
+        $teamCategory = $this->em->getRepository(TeamCategory::class)->findByExternalId($categoryId);
         if (!$teamCategory) {
             throw new NotFoundHttpException(sprintf('Team category with ID %s not found', $categoryId));
         }
@@ -141,13 +140,17 @@ public function viewAction(Request $request, SubmissionService $submissionServic
 
         $data = [
             'teamCategory' => $teamCategory,
+            'previousNext' => $this->getPreviousAndNextObjectIds(
+                TeamCategory::class,
+                $teamCategory->getExternalid(),
+            ),
             'submissions' => $submissions,
             'submissionCounts' => $submissionCounts,
             'showContest' => count($this->dj->getCurrentContests(honorCookie: true)) > 1,
             'showExternalResult' => $this->dj->shadowMode(),
             'refresh' => [
                 'after' => 15,
-                'url' => $this->generateUrl('jury_team_category', ['categoryId' => $teamCategory->getCategoryid()]),
+                'url' => $this->generateUrl('jury_team_category', ['categoryId' => $teamCategory->getExternalid()]),
                 'ajax' => true,
             ],
         ];
@@ -162,10 +165,10 @@ public function viewAction(Request $request, SubmissionService $submissionServic
     }
 
     #[IsGranted('ROLE_ADMIN')]
-    #[Route(path: '/{categoryId<\d+>}/edit', name: 'jury_team_category_edit')]
-    public function editAction(Request $request, int $categoryId): Response
+    #[Route(path: '/{categoryId}/edit', name: 'jury_team_category_edit')]
+    public function editAction(Request $request, string $categoryId): Response
     {
-        $teamCategory = $this->em->getRepository(TeamCategory::class)->find($categoryId);
+        $teamCategory = $this->em->getRepository(TeamCategory::class)->findByExternalId($categoryId);
         if (!$teamCategory) {
             throw new NotFoundHttpException(sprintf('Team category with ID %s not found', $categoryId));
         }
@@ -193,7 +196,7 @@ public function editAction(Request $request, int $categoryId): Response
                 }
             }
             $this->addFlash('scoreboard_refresh', 'If the category sort order was changed, it may be necessary to recalculate any cached scoreboards.');
-            return $this->redirectToRoute('jury_team_category', ['categoryId' => $teamCategory->getCategoryid()]);
+            return $this->redirectToRoute('jury_team_category', ['categoryId' => $teamCategory->getExternalid()]);
         }
 
         return $this->render('jury/team_category_edit.html.twig', [
@@ -203,10 +206,10 @@ public function editAction(Request $request, int $categoryId): Response
     }
 
     #[IsGranted('ROLE_ADMIN')]
-    #[Route(path: '/{categoryId<\d+>}/delete', name: 'jury_team_category_delete')]
-    public function deleteAction(Request $request, int $categoryId): Response
+    #[Route(path: '/{categoryId}/delete', name: 'jury_team_category_delete')]
+    public function deleteAction(Request $request, string $categoryId): Response
     {
-        $teamCategory = $this->em->getRepository(TeamCategory::class)->find($categoryId);
+        $teamCategory = $this->em->getRepository(TeamCategory::class)->findByExternalId($categoryId);
         if (!$teamCategory) {
             throw new NotFoundHttpException(sprintf('Team category with ID %s not found', $categoryId));
         }
@@ -215,7 +218,7 @@ public function deleteAction(Request $request, int $categoryId): Response
     }
 
     #[IsGranted('ROLE_ADMIN')]
-    #[Route(path: '/add', name: 'jury_team_category_add')]
+    #[Route(path: '/add', name: 'jury_team_category_add', priority: 1)]
     public function addAction(Request $request): Response
     {
         $teamCategory = new TeamCategory();
@@ -226,7 +229,7 @@ public function addAction(Request $request): Response
 
         if ($response = $this->processAddFormForExternalIdEntity(
             $form, $teamCategory,
-            fn() => $this->generateUrl('jury_team_category', ['categoryId' => $teamCategory->getCategoryid()])
+            fn() => $this->generateUrl('jury_team_category', ['categoryId' => $teamCategory->getExternalid()])
         )) {
             return $response;
         }
@@ -237,26 +240,26 @@ public function addAction(Request $request): Response
     }
 
     #[IsGranted('ROLE_ADMIN')]
-    #[Route(path: '/delete-multiple', name: 'jury_team_category_delete_multiple', methods: ['GET', 'POST'])]
+    #[Route(path: '/delete-multiple', name: 'jury_team_category_delete_multiple', methods: ['GET', 'POST'], priority: 1)]
     public function deleteMultipleAction(Request $request): Response
     {
         return $this->deleteMultiple(
             $request,
             TeamCategory::class,
-            'categoryid',
+            'externalid',
             'jury_team_categories',
             'No categories could be deleted.'
         );
     }
 
-    #[Route(path: '/{categoryId<\d+>}/request-remaining', name: 'jury_team_category_request_remaining')]
+    #[Route(path: '/{categoryId}/request-remaining', name: 'jury_team_category_request_remaining')]
     public function requestRemainingRunsWholeTeamCategoryAction(string $categoryId): RedirectResponse
     {
         $category = $this->em->getRepository(TeamCategory::class)->find($categoryId);
         if (!$category) {
             throw new NotFoundHttpException(sprintf('Team category with ID %s not found', $categoryId));
         }
-        $contestId = $this->dj->getCurrentContest()->getCid();
+        $contestId = $this->dj->getCurrentContest()->getExternalid();
         $this->judgeRemaining(contestId: $contestId, categoryId: $categoryId);
         return $this->redirectToRoute('jury_team_category', ['categoryId' => $categoryId]);
     }
diff --git a/webapp/src/Controller/Jury/TeamController.php b/webapp/src/Controller/Jury/TeamController.php
index 54522fcf26..87ae2dc466 100644
--- a/webapp/src/Controller/Jury/TeamController.php
+++ b/webapp/src/Controller/Jury/TeamController.php
@@ -5,6 +5,8 @@
 use App\Controller\BaseController;
 use App\DataTransferObject\SubmissionRestriction;
 use App\Entity\Contest;
+use App\Entity\Language;
+use App\Entity\Problem;
 use App\Entity\Role;
 use App\Entity\Team;
 use App\Entity\User;
@@ -89,8 +91,7 @@ public function indexAction(): Response
         $teams_that_solved = array_column($teams_that_solved, 'num_correct', 'teamid');
 
         $table_fields = [
-            'teamid' => ['title' => 'ID', 'sort' => true, 'default_sort' => true],
-            'externalid' => ['title' => 'external ID', 'sort' => true],
+            'externalid' => ['title' => 'ID', 'sort' => true, 'default_sort' => true],
             'label' => ['title' => 'label', 'sort' => true,],
             'effective_name' => ['title' => 'name', 'sort' => true,],
             'category' => ['title' => 'category', 'sort' => true,],
@@ -118,7 +119,7 @@ public function indexAction(): Response
             $teamdata    = [];
             $teamactions = [];
 
-            $this->addEntityCheckbox($teamdata, $t, $t->getTeamid(), 'team-checkbox', fn(Team $team) => !$team->isLocked());
+            $this->addEntityCheckbox($teamdata, $t, $t->getExternalid(), 'team-checkbox', fn(Team $team) => !$team->isLocked());
 
             // Get whatever fields we can from the team object itself.
             foreach ($table_fields as $k => $v) {
@@ -153,14 +154,14 @@ public function indexAction(): Response
                     'icon' => 'edit',
                     'title' => 'edit this team',
                     'link' => $this->generateUrl('jury_team_edit', [
-                        'teamId' => $t->getTeamid(),
+                        'teamId' => $t->getExternalid(),
                     ]),
                 ];
                 $teamactions[] = [
                     'icon' => 'trash-alt',
                     'title' => 'delete this team',
                     'link' => $this->generateUrl('jury_team_delete', [
-                        'teamId' => $t->getTeamId(),
+                        'teamId' => $t->getExternalid(),
                     ]),
                     'ajaxModal' => true,
                 ];
@@ -169,7 +170,7 @@ public function indexAction(): Response
                 'icon' => 'envelope',
                 'title' => 'send clarification to this team',
                 'link' => $this->generateUrl('jury_clarification_new', [
-                    'teamto' => $t->getTeamId(),
+                    'teamto' => $t->getExternalid(),
                 ])
             ];
 
@@ -216,8 +217,8 @@ public function indexAction(): Response
             $teams_table[] = [
                 'data' => $teamdata,
                 'actions' => $teamactions,
-                'link' => $this->generateUrl('jury_team', ['teamId' => $t->getTeamId()]),
-                'cssclass' => ($t->getCategory() ? ("category" . $t->getCategory()->getCategoryId()) : '') .
+                'link' => $this->generateUrl('jury_team', ['teamId' => $t->getExternalid()]),
+                'cssclass' => ($t->getCategory() ? ("category" . $t->getCategory()->getExternalid()) : '') .
                     ($t->getEnabled() ? '' : ' disabled'),
             ];
         }
@@ -227,16 +228,16 @@ public function indexAction(): Response
         ]);
     }
 
-    #[Route(path: '/{teamId<\d+>}', name: 'jury_team')]
+    #[Route(path: '/{teamId}', name: 'jury_team')]
     public function viewAction(
         Request $request,
-        int $teamId,
+        string $teamId,
         ScoreboardService $scoreboardService,
         SubmissionService $submissionService,
         #[MapQueryParameter]
-        ?int $cid = null,
+        ?string $cid = null,
     ): Response {
-        $team = $this->em->getRepository(Team::class)->find($teamId);
+        $team = $this->em->getRepository(Team::class)->findByExternalId($teamId);
         if (!$team) {
             throw new NotFoundHttpException(sprintf('Team with ID %s not found', $teamId));
         }
@@ -252,6 +253,10 @@ public function viewAction(
                 'ajax' => true,
             ],
             'team' => $team,
+            'previousNext' => $this->getPreviousAndNextObjectIds(
+                Team::class,
+                $team->getExternalid(),
+            ),
             'showAffiliations' => (bool)$this->config->get('show_affiliations'),
             'showFlags' => (bool)$this->config->get('show_flags'),
             'showContest' => count($this->dj->getCurrentContests()) > 1,
@@ -266,7 +271,7 @@ public function viewAction(
 
         if ($currentContest) {
             $scoreboard = $scoreboardService
-                ->getTeamScoreboard($currentContest, $teamId, true);
+                ->getTeamScoreboard($currentContest, $team->getExternalid(), true);
             $data = array_merge(
                 $data,
                 $scoreboardService->getScoreboardTwigData(
@@ -289,12 +294,17 @@ public function viewAction(
                     'judgehost' => 'judgehost',
                     default => throw new BadRequestHttpException(sprintf('Restriction on %s not allowed.', $key)),
                 };
-                $restrictions->$key = is_numeric($value) ? (int)$value : $value;
+                $restrictionValue = match ($key) {
+                    'problemId' => $this->em->getRepository(Problem::class)->findByExternalId($value)->getProbid(),
+                    'languageId' => $this->em->getRepository(Language::class)->findByExternalId($value)->getLangid(),
+                    default => $value,
+                };
+                $restrictions->$key = is_numeric($restrictionValue) ? (int)$restrictionValue : $restrictionValue;
                 $restrictionTexts[] = sprintf('%s %s', $restrictionKeyText, $value);
             }
             $restrictionText = implode(', ', $restrictionTexts);
         }
-        $restrictions->teamId = $teamId;
+        $restrictions->teamId = $team->getTeamid();
         [$submissions, $submissionCounts] =
             $submissionService->getSubmissionList(
                 $this->dj->getCurrentContests(honorCookie: true),
@@ -318,10 +328,10 @@ public function viewAction(
     }
 
     #[IsGranted('ROLE_ADMIN')]
-    #[Route(path: '/{teamId<\d+>}/edit', name: 'jury_team_edit')]
-    public function editAction(Request $request, int $teamId): Response
+    #[Route(path: '/{teamId}/edit', name: 'jury_team_edit')]
+    public function editAction(Request $request, string $teamId): Response
     {
-        $team = $this->em->getRepository(Team::class)->find($teamId);
+        $team = $this->em->getRepository(Team::class)->findByExternalId($teamId);
         if (!$team) {
             throw new NotFoundHttpException(sprintf('Team with ID %s not found', $teamId));
         }
@@ -334,7 +344,7 @@ public function editAction(Request $request, int $teamId): Response
             $this->possiblyAddUser($team);
             $this->assetUpdater->updateAssets($team);
             $this->saveEntity($team, $team->getTeamid(), false);
-            return $this->redirectToRoute('jury_team', ['teamId' => $team->getTeamid()]);
+            return $this->redirectToRoute('jury_team', ['teamId' => $team->getExternalid()]);
         }
 
         return $this->render('jury/team_edit.html.twig', [
@@ -344,10 +354,10 @@ public function editAction(Request $request, int $teamId): Response
     }
 
     #[IsGranted('ROLE_ADMIN')]
-    #[Route(path: '/{teamId<\d+>}/delete', name: 'jury_team_delete')]
-    public function deleteAction(Request $request, int $teamId): Response
+    #[Route(path: '/{teamId}/delete', name: 'jury_team_delete')]
+    public function deleteAction(Request $request, string $teamId): Response
     {
-        $team = $this->em->getRepository(Team::class)->find($teamId);
+        $team = $this->em->getRepository(Team::class)->findByExternalId($teamId);
         if (!$team) {
             throw new NotFoundHttpException(sprintf('Team with ID %s not found', $teamId));
         }
@@ -356,13 +366,13 @@ public function deleteAction(Request $request, int $teamId): Response
     }
 
     #[IsGranted('ROLE_ADMIN')]
-    #[Route(path: '/delete-multiple', name: 'jury_team_delete_multiple', methods: ['GET', 'POST'])]
+    #[Route(path: '/delete-multiple', name: 'jury_team_delete_multiple', methods: ['GET', 'POST'], priority: 1)]
     public function deleteMultipleAction(Request $request): Response
     {
         return $this->deleteMultiple(
             $request,
             Team::class,
-            'teamid',
+            'externalid',
             'jury_teams',
             'No teams could be deleted (they might be in a locked contest).',
             fn(Team $team) => !$team->isLocked()
@@ -370,7 +380,7 @@ public function deleteMultipleAction(Request $request): Response
     }
 
     #[IsGranted('ROLE_ADMIN')]
-    #[Route(path: '/add', name: 'jury_team_add')]
+    #[Route(path: '/add', name: 'jury_team_add', priority: 1)]
     public function addAction(Request $request): Response
     {
         $team = new Team();
@@ -381,7 +391,7 @@ public function addAction(Request $request): Response
 
         if ($response = $this->processAddFormForExternalIdEntity(
             $form, $team,
-            fn() => $this->generateUrl('jury_team', ['teamId' => $team->getTeamid()]),
+            fn() => $this->generateUrl('jury_team', ['teamId' => $team->getExternalid()]),
             function () use ($team) {
                 $this->possiblyAddUser($team);
                 $this->em->persist($team);
diff --git a/webapp/src/Controller/Jury/UserController.php b/webapp/src/Controller/Jury/UserController.php
index f696d82ae1..80380f5de8 100644
--- a/webapp/src/Controller/Jury/UserController.php
+++ b/webapp/src/Controller/Jury/UserController.php
@@ -62,7 +62,7 @@ public function indexAction(): Response
 
         $table_fields = [
             'username'   => ['title' => 'username', 'sort' => true, 'default_sort' => true],
-            'externalid' => ['title' => 'external ID', 'sort' => true],
+            'externalid' => ['title' => 'ID', 'sort' => true],
             'name'       => ['title' => 'name', 'sort' => true],
             'email'      => ['title' => 'email', 'sort' => true],
             'user_roles' => ['title' => 'roles', 'sort' => true],
@@ -86,7 +86,7 @@ public function indexAction(): Response
             $userdata    = [];
             $useractions = [];
 
-            $this->addEntityCheckbox($userdata, $u, $u->getUserid(), 'user-checkbox', fn(User $user) => $user->getUserid() !== $this->dj->getUser()->getUserid());
+            $this->addEntityCheckbox($userdata, $u, $u->getExternalid(), 'user-checkbox', fn(User $user) => $user->getUserid() !== $this->dj->getUser()->getUserid());
 
             // Get whatever fields we can from the user object itself.
             foreach ($table_fields as $k => $v) {
@@ -105,13 +105,12 @@ public function indexAction(): Response
             if ($u->getTeam()) {
                 $userdata['teamid'] = [
                     'value' => $u->getTeam(),
-                    'idPrefix' => 't',
                 ];
                 $userdata['team'] = [
                     'value' => $u->getTeamName(),
-                    'sortvalue' => $u->getTeam()->getTeamid(),
+                    'sortvalue' => $u->getTeam()->getExternalid(),
                     'link' => $this->generateUrl('jury_team', [
-                        'teamId' => $u->getTeam()->getTeamid(),
+                        'teamId' => $u->getTeam()->getExternalid(),
                     ]),
                     'title' => $u->getTeam()->getEffectiveName(),
                 ];
@@ -139,14 +138,14 @@ public function indexAction(): Response
                     'icon' => 'edit',
                     'title' => 'edit this user',
                     'link' => $this->generateUrl('jury_user_edit', [
-                        'userId' => $u->getUserid(),
+                        'userId' => $u->getExternalid(),
                     ])
                 ];
                 $useractions[] = [
                     'icon' => 'trash-alt',
                     'title' => 'delete this user',
                     'link' => $this->generateUrl('jury_user_delete', [
-                        'userId' => $u->getUserid(),
+                        'userId' => $u->getExternalid(),
                     ]),
                     'ajaxModal' => true,
                 ];
@@ -164,7 +163,7 @@ public function indexAction(): Response
             $users_table[] = [
                 'data' => $userdata,
                 'actions' => $useractions,
-                'link' => $this->generateUrl('jury_user', ['userId' => $u->getUserid()]),
+                'link' => $this->generateUrl('jury_user', ['userId' => $u->getExternalid()]),
                 'cssclass' => $u->getEnabled() ? '' : 'disabled',
             ];
         }
@@ -175,10 +174,10 @@ public function indexAction(): Response
         ]);
     }
 
-    #[Route(path: '/{userId<\d+>}', name: 'jury_user')]
-    public function viewAction(Request $request, int $userId, SubmissionService $submissionService): Response
+    #[Route(path: '/{userId}', name: 'jury_user')]
+    public function viewAction(Request $request, string $userId, SubmissionService $submissionService): Response
     {
-        $user = $this->em->getRepository(User::class)->find($userId);
+        $user = $this->em->getRepository(User::class)->findByExternalId($userId);
         if (!$user) {
             throw new NotFoundHttpException(sprintf('User with ID %s not found', $userId));
         }
@@ -192,6 +191,11 @@ public function viewAction(Request $request, int $userId, SubmissionService $sub
 
         return $this->render('jury/user.html.twig', [
             'user' => $user,
+            'previousNext' => $this->getPreviousAndNextObjectIds(
+                User::class,
+                $user->getExternalid(),
+                orderBy: ['e.username' => 'ASC'],
+            ),
             'submissions' => $submissions,
             'submissionCounts' => $submissionCounts,
             'showContest' => count($this->dj->getCurrentContests(honorCookie: true)) > 1,
@@ -219,10 +223,10 @@ public function checkPasswordLength(User $user, FormInterface $form): ?Response
     }
 
     #[IsGranted('ROLE_ADMIN')]
-    #[Route(path: '/{userId<\d+>}/edit', name: 'jury_user_edit')]
-    public function editAction(Request $request, int $userId): Response
+    #[Route(path: '/{userId}/edit', name: 'jury_user_edit')]
+    public function editAction(Request $request, string $userId): Response
     {
-        $user = $this->em->getRepository(User::class)->find($userId);
+        $user = $this->em->getRepository(User::class)->findByExternalId($userId);
         if (!$user) {
             throw new NotFoundHttpException(sprintf('User with ID %s not found', $userId));
         }
@@ -248,7 +252,7 @@ public function editAction(Request $request, int $userId): Response
                 $this->tokenStorage->setToken($token);
             }
 
-            return $this->redirectToRoute('jury_user', ['userId' => $user->getUserid()]);
+            return $this->redirectToRoute('jury_user', ['userId' => $user->getExternalid()]);
         }
 
         return $this->render('jury/user_edit.html.twig', [
@@ -258,10 +262,10 @@ public function editAction(Request $request, int $userId): Response
     }
 
     #[IsGranted('ROLE_ADMIN')]
-    #[Route(path: '/{userId<\d+>}/delete', name: 'jury_user_delete')]
-    public function deleteAction(Request $request, int $userId): Response
+    #[Route(path: '/{userId}/delete', name: 'jury_user_delete')]
+    public function deleteAction(Request $request, string $userId): Response
     {
-        $user = $this->em->getRepository(User::class)->find($userId);
+        $user = $this->em->getRepository(User::class)->findByExternalId($userId);
         if (!$user) {
             throw new NotFoundHttpException(sprintf('User with ID %s not found', $userId));
         }
@@ -270,7 +274,7 @@ public function deleteAction(Request $request, int $userId): Response
     }
 
     #[IsGranted('ROLE_ADMIN')]
-    #[Route(path: '/add', name: 'jury_user_add')]
+    #[Route(path: '/add', name: 'jury_user_add', priority: 1)]
     public function addAction(
         Request $request,
         #[MapQueryParameter]
@@ -287,7 +291,7 @@ public function addAction(
 
         if ($response = $this->processAddFormForExternalIdEntity(
             $form, $user,
-            fn() => $this->generateUrl('jury_user', ['userId' => $user->getUserid()]),
+            fn() => $this->generateUrl('jury_user', ['userId' => $user->getExternalid()]),
             function () use ($user, $form) {
                 if ($errorResult = $this->checkPasswordLength($user, $form)) {
                     return $errorResult;
@@ -307,7 +311,7 @@ function () use ($user, $form) {
     }
 
     #[IsGranted('ROLE_ADMIN')]
-    #[Route(path: '/generate-passwords', name: 'jury_generate_passwords')]
+    #[Route(path: '/generate-passwords', name: 'jury_generate_passwords', priority: 1)]
     public function generatePasswordsAction(Request $request): Response
     {
         $form = $this->createForm(GeneratePasswordsType::class);
@@ -345,7 +349,7 @@ public function generatePasswordsAction(Request $request): Response
                 if ($doit) {
                     $newpass = Utils::generatePassword(false);
                     $user->setPlainPassword($newpass);
-                    $this->dj->auditlog('user', $user->getUserid(), 'set password');
+                    $this->dj->auditlog('user', $user->getExternalid(), 'set password');
                     $changes[] = [
                             'type' => $role,
                             'fullname' => $user->getName(),
@@ -372,7 +376,7 @@ public function generatePasswordsAction(Request $request): Response
     }
 
     #[IsGranted('ROLE_ADMIN')]
-    #[Route(path: '/reset_login_status', name: 'jury_reset_login_status')]
+    #[Route(path: '/reset_login_status', name: 'jury_reset_login_status', priority: 1)]
     public function resetTeamLoginStatus(Request $request): Response
     {
         /** @var Role $teamRole */
@@ -393,13 +397,13 @@ public function resetTeamLoginStatus(Request $request): Response
     }
 
     #[IsGranted('ROLE_ADMIN')]
-    #[Route(path: '/delete-multiple', name: 'jury_user_delete_multiple', methods: ['GET', 'POST'])]
+    #[Route(path: '/delete-multiple', name: 'jury_user_delete_multiple', methods: ['GET', 'POST'], priority: 1)]
     public function deleteMultipleAction(Request $request): Response
     {
         return $this->deleteMultiple(
             $request,
             User::class,
-            'userid',
+            'externalid',
             'jury_users',
             'No users could be deleted (you cannot delete your own account).',
             fn(User $user) => $user->getUserid() !== $this->dj->getUser()->getUserid()
diff --git a/webapp/src/Controller/PublicController.php b/webapp/src/Controller/PublicController.php
index 6a22a2d6e1..96380e09b3 100644
--- a/webapp/src/Controller/PublicController.php
+++ b/webapp/src/Controller/PublicController.php
@@ -74,7 +74,7 @@ public function scoreboardAction(
 
             if ($requestedContest = $this->getContestFromRequest($contestId)) {
                 $contest                  = $requestedContest;
-                $refreshParams['contest'] = $contest->getCid();
+                $refreshParams['contest'] = $contest->getExternalid();
             }
 
             $refreshUrl = sprintf('?%s', http_build_query($refreshParams));
@@ -143,7 +143,7 @@ protected function getContestFromRequest(?string $contestId = null): ?Contest
             } else {
                 // Find the contest with the given ID.
                 foreach ($this->dj->getCurrentContests(onlyPublic: true) as $possibleContest) {
-                    if ($possibleContest->getCid() == $contestId || $possibleContest->getExternalid() == $contestId) {
+                    if ($possibleContest->getExternalid() == $contestId) {
                         $contest = $possibleContest;
                         break;
                     }
@@ -158,23 +158,23 @@ protected function getContestFromRequest(?string $contestId = null): ?Contest
         return $contest;
     }
 
-    #[Route(path: '/change-contest/{contestId<-?\d+>}', name: 'public_change_contest')]
-    public function changeContestAction(Request $request, RouterInterface $router, int $contestId): Response
+    #[Route(path: '/change-contest/{contestId}', name: 'public_change_contest')]
+    public function changeContestAction(Request $request, RouterInterface $router, string $contestId): Response
     {
         if ($this->isLocalReferer($router, $request)) {
             $response = new RedirectResponse($request->headers->get('referer'));
         } else {
             $response = $this->redirectToRoute('public_index');
         }
-        return $this->dj->setCookie('domjudge_cid', (string)$contestId, 0, null, '', false, false,
+        return $this->dj->setCookie('domjudge_cid', $contestId, 0, null, '', false, false,
                                                  $response);
     }
 
-    #[Route(path: '/team/{teamId<\d+>}', name: 'public_team')]
-    public function teamAction(Request $request, int $teamId): Response
+    #[Route(path: '/team/{teamId}', name: 'public_team')]
+    public function teamAction(Request $request, string $teamId): Response
     {
         /** @var Team|null $team */
-        $team             = $this->em->getRepository(Team::class)->find($teamId);
+        $team             = $this->em->getRepository(Team::class)->findByExternalId($teamId);
         if ($team && $team->getCategory() && !$team->getCategory()->getVisible()) {
             $team = null;
         }
@@ -203,11 +203,11 @@ public function problemsAction(): Response
             $this->dj->getTwigDataForProblemsAction($this->stats));
     }
 
-    #[Route(path: '/problems/{probId<\d+>}/statement', name: 'public_problem_statement')]
-    public function problemStatementAction(int $probId): StreamedResponse
+    #[Route(path: '/problems/{probId}/statement', name: 'public_problem_statement')]
+    public function problemStatementAction(string $probId): StreamedResponse
     {
         return $this->getBinaryFile($probId, function (
-            int $probId,
+            string $probId,
             Contest $contest,
             ContestProblem $contestProblem
         ) {
@@ -235,20 +235,20 @@ public function contestProblemsetAction(): StreamedResponse
     /**
      * @throws NonUniqueResultException
      */
-    #[Route(path: '/{probId<\d+>}/attachment/{attachmentId<\d+>}', name: 'public_problem_attachment')]
-    public function attachmentAction(int $probId, int $attachmentId): StreamedResponse
+    #[Route(path: '/{probId}/attachment/{attachmentId<\d+>}', name: 'public_problem_attachment')]
+    public function attachmentAction(string $probId, int $attachmentId): StreamedResponse
     {
         return $this->getBinaryFile($probId, fn(
-            int $probId,
+            string $probId,
             Contest $contest,
             ContestProblem $contestProblem
         ) => $this->dj->getAttachmentStreamedResponse($contestProblem, $attachmentId));
     }
 
-    #[Route(path: '/{probId<\d+>}/samples.zip', name: 'public_problem_sample_zip')]
-    public function sampleZipAction(int $probId): StreamedResponse
+    #[Route(path: '/{probId}/samples.zip', name: 'public_problem_sample_zip')]
+    public function sampleZipAction(string $probId): StreamedResponse
     {
-        return $this->getBinaryFile($probId, function (int $probId, Contest $contest, ContestProblem $contestProblem) {
+        return $this->getBinaryFile($probId, function (string $probId, Contest $contest, ContestProblem $contestProblem) {
             return $this->dj->getSamplesZipStreamedResponse($contestProblem);
         });
     }
@@ -258,16 +258,13 @@ public function sampleZipAction(int $probId): StreamedResponse
      *
      * Shared code between testcases, problem text and attachments.
      */
-    protected function getBinaryFile(int $probId, callable $response): StreamedResponse
+    protected function getBinaryFile(string $probId, callable $response): StreamedResponse
     {
         $contest = $this->dj->getCurrentContest(onlyPublic: true);
         if (!$contest || !$contest->getFreezeData()->started()) {
             throw new NotFoundHttpException(sprintf('Problem p%d not found or not available', $probId));
         }
-        $contestProblem = $this->em->getRepository(ContestProblem::class)->find([
-            'problem' => $probId,
-            'contest' => $contest,
-        ]);
+        $contestProblem = $this->em->getRepository(ContestProblem::class)->findByProblemAndContest($contest, $probId);
         if (!$contestProblem) {
             throw new NotFoundHttpException(sprintf('Problem p%d not found or not available', $probId));
         }
@@ -285,7 +282,7 @@ public function submissionsAction(Request $request, string $teamId, string $prob
         }
 
         /** @var Team|null $team */
-        $team = $this->em->getRepository(Team::class)->findOneBy(['externalid' => $teamId]);
+        $team = $this->em->getRepository(Team::class)->findByExternalId($teamId);
         if ($team && $team->getCategory() && !$team->getCategory()->getVisible()) {
             $team = null;
         }
@@ -379,7 +376,7 @@ public function submissionsDataAction(Request $request, ?string $teamId, ?string
             }
             $submissionData[$teamKey][$problemKey][] = [
                 'time' => $this->twigExtension->printtime($submission->getSubmittime(), contest: $contest),
-                'language' => $submission->getLanguageId(),
+                'language' => $submission->getLanguage()->getName(),
                 'verdict' => $this->submissionVerdict($submission, $contest, $verificationRequired),
             ];
         }
diff --git a/webapp/src/Controller/Team/ClarificationController.php b/webapp/src/Controller/Team/ClarificationController.php
index c6c5079ff1..d1d4771bf3 100644
--- a/webapp/src/Controller/Team/ClarificationController.php
+++ b/webapp/src/Controller/Team/ClarificationController.php
@@ -45,17 +45,17 @@ public function __construct(
         parent::__construct($em, $eventLogService, $dj, $kernel);
     }
 
-    #[Route(path: '/clarifications/by-problem/{probId<\d+>}', name: 'team_clarification_by_prob')]
-    public function viewByProblemAction(Request $request, int $probId): Response
+    #[Route(path: '/clarifications/by-problem/{probId}', name: 'team_clarification_by_prob')]
+    public function viewByProblemAction(Request $request, string $probId): Response
     {
         $user    = $this->dj->getUser();
         $team    = $user->getTeam();
         $teamId  = $team->getTeamid();
         $contest = $this->dj->getCurrentContest($teamId);
 
-        $problem = $this->em->getRepository(Problem::class)->find($probId);
+        $problem = $this->em->getRepository(Problem::class)->findByExternalId($probId);
         if ($problem === null) {
-            throw new NotFoundHttpException(sprintf('Problem %d not found', $probId));
+            throw new NotFoundHttpException(sprintf('Problem %s not found', $probId));
         }
         $contestProblem = $problem->getContestProblems();
         $foundProblemInContest = false;
@@ -66,7 +66,7 @@ public function viewByProblemAction(Request $request, int $probId): Response
             }
         }
         if (!$foundProblemInContest) {
-            throw new NotFoundHttpException(sprintf('Problem %d not in current contest', $probId));
+            throw new NotFoundHttpException(sprintf('Problem %s not in current contest', $probId));
         }
 
         /** @var Clarification[] $clarifications */
@@ -103,8 +103,8 @@ public function viewByProblemAction(Request $request, int $probId): Response
     /**
      * @throws NonUniqueResultException
      */
-    #[Route(path: '/clarifications/{clarId<\d+>}', name: 'team_clarification')]
-    public function viewAction(Request $request, int $clarId): Response
+    #[Route(path: '/clarifications/{clarId}', name: 'team_clarification')]
+    public function viewAction(Request $request, string $clarId): Response
     {
         $categories = $this->config->get('clar_categories');
         $user       = $this->dj->getUser();
@@ -118,7 +118,7 @@ public function viewAction(Request $request, int $clarId): Response
             ->leftJoin('p.contest_problems', 'cp', Join::WITH, 'cp.contest = :contest')
             ->select('c, p, co')
             ->andWhere('c.contest = :contest')
-            ->andWhere('c.clarid = :clarId')
+            ->andWhere('c.externalid = :clarId')
             ->setParameter('contest', $contest)
             ->setParameter('clarId', $clarId)
             ->getQuery()
@@ -127,9 +127,9 @@ public function viewAction(Request $request, int $clarId): Response
         $formData = [];
         if ($clarification) {
             if ($clarification->getProblem()) {
-                $formData['subject'] = sprintf('%d-%d', $clarification->getContest()->getCid(), $clarification->getProblem()->getProbid());
+                $formData['subject'] = sprintf('%s|%s', $clarification->getContest()->getExternalid(), $clarification->getProblem()->getExternalid());
             } else {
-                $formData['subject'] = sprintf('%d-%s', $clarification->getContest()->getCid(), $clarification->getCategory());
+                $formData['subject'] = sprintf('%s#%s', $clarification->getContest()->getExternalid(), $clarification->getCategory());
             }
 
             $formData['message'] = "> " . str_replace("\n", "\n> ", Utils::wrapUnquoted($clarification->getBody())) . "\n\n";
@@ -149,7 +149,7 @@ public function viewAction(Request $request, int $clarId): Response
         }
 
         if ($clarification === null) {
-            throw new NotFoundHttpException(sprintf('Clarification %d not found', $clarId));
+            throw new NotFoundHttpException(sprintf('Clarification %s not found', $clarId));
         }
 
         if (!$team->canViewClarification($clarification)) {
@@ -185,7 +185,7 @@ public function viewAction(Request $request, int $clarId): Response
         }
     }
 
-    #[Route(path: '/clarifications/add', name: 'team_clarification_add')]
+    #[Route(path: '/clarifications/add', name: 'team_clarification_add', priority: 1)]
     public function addAction(Request $request): Response
     {
         $categories = $this->config->get('clar_categories');
@@ -227,15 +227,15 @@ private function newClarificationHelper(
         Team $team
     ): void {
         $formData = $form->getData();
-        // First part will always be the contest ID, as Symfony will validate this.
-        [, $problemId] = explode('-', $formData['subject']);
+        // First part will always be the contest external ID, as Symfony will validate this.
         $problem = null;
         $category = null;
         $queue = null;
-        if (!ctype_digit($problemId)) {
-            $category = $problemId;
+        if (str_contains($formData['subject'], '#')) {
+            [, $category] = explode('#', $formData['subject']);
         } else {
-            $problem = $this->em->getRepository(Problem::class)->find($problemId);
+            [, $problemId] = explode('|', $formData['subject']);
+            $problem = $this->em->getRepository(Problem::class)->findByExternalId($problemId);
             $queue = $this->config->get('clar_default_problem_queue');
             if ($queue === "") {
                 $queue = null;
@@ -255,8 +255,8 @@ private function newClarificationHelper(
         $this->em->persist($newClarification);
         $this->em->flush();
 
-        $this->dj->auditlog('clarification', $newClarification->getClarid(), 'added', null, null,
-            $contest->getCid());
+        $this->dj->auditlog('clarification', $newClarification->getExternalid(), 'added', null, null,
+            $contest->getExternalid());
         $this->eventLogService->log('clarification', $newClarification->getClarid(), 'create', $contest->getCid());
 
         $this->addFlash('success', 'Clarification sent to the jury');
diff --git a/webapp/src/Controller/Team/MiscController.php b/webapp/src/Controller/Team/MiscController.php
index 5b894163d4..437c6831f0 100644
--- a/webapp/src/Controller/Team/MiscController.php
+++ b/webapp/src/Controller/Team/MiscController.php
@@ -73,7 +73,7 @@ public function homeAction(Request $request): Response
         ];
         if ($contest) {
             $scoreboard = $this->scoreboardService
-                ->getTeamScoreboard($contest, $teamId, false);
+                ->getTeamScoreboard($contest, $team->getExternalid(), false);
             $data = array_merge(
                 $data,
                 $this->scoreboardService->getScoreboardTwigData(
@@ -151,15 +151,15 @@ public function updatesAction(): JsonResponse
         return $this->json(['unread_clarifications' => $this->dj->getUnreadClarifications()]);
     }
 
-    #[Route(path: '/change-contest/{contestId<-?\d+>}', name: 'team_change_contest')]
-    public function changeContestAction(Request $request, RouterInterface $router, int $contestId): Response
+    #[Route(path: '/change-contest/{contestId}', name: 'team_change_contest')]
+    public function changeContestAction(Request $request, RouterInterface $router, string $contestId): Response
     {
         if ($this->isLocalReferer($router, $request)) {
             $response = new RedirectResponse($request->headers->get('referer'));
         } else {
             $response = $this->redirectToRoute('team_index');
         }
-        return $this->dj->setCookie('domjudge_cid', (string)$contestId, 0, null, '', false, false,
+        return $this->dj->setCookie('domjudge_cid', $contestId, 0, null, '', false, false,
                                                  $response);
     }
 
diff --git a/webapp/src/Controller/Team/ProblemController.php b/webapp/src/Controller/Team/ProblemController.php
index 9374ee46b4..9a86d50826 100644
--- a/webapp/src/Controller/Team/ProblemController.php
+++ b/webapp/src/Controller/Team/ProblemController.php
@@ -51,11 +51,11 @@ public function problemsAction(): Response
     }
 
 
-    #[Route(path: '/problems/{probId<\d+>}/statement', name: 'team_problem_statement')]
-    public function problemStatementAction(int $probId): StreamedResponse
+    #[Route(path: '/problems/{probId}/statement', name: 'team_problem_statement')]
+    public function problemStatementAction(string $probId): StreamedResponse
     {
         return $this->getBinaryFile($probId, function (
-            int $probId,
+            string $probId,
             Contest $contest,
             ContestProblem $contestProblem
         ) {
@@ -73,20 +73,20 @@ public function problemStatementAction(int $probId): StreamedResponse
     /**
      * @throws NonUniqueResultException
      */
-    #[Route(path: '/{probId<\d+>}/attachment/{attachmentId<\d+>}', name: 'team_problem_attachment')]
-    public function attachmentAction(int $probId, int $attachmentId): StreamedResponse
+    #[Route(path: '/{probId}/attachment/{attachmentId<\d+>}', name: 'team_problem_attachment')]
+    public function attachmentAction(string $probId, int $attachmentId): StreamedResponse
     {
         return $this->getBinaryFile($probId, fn(
-            int $probId,
+            string $probId,
             Contest $contest,
             ContestProblem $contestProblem
         ) => $this->dj->getAttachmentStreamedResponse($contestProblem, $attachmentId));
     }
 
-    #[Route(path: '/{probId<\d+>}/samples.zip', name: 'team_problem_sample_zip')]
-    public function sampleZipAction(int $probId): StreamedResponse
+    #[Route(path: '/{probId}/samples.zip', name: 'team_problem_sample_zip')]
+    public function sampleZipAction(string $probId): StreamedResponse
     {
-        return $this->getBinaryFile($probId, function (int $probId, Contest $contest, ContestProblem $contestProblem) {
+        return $this->getBinaryFile($probId, function (string $probId, Contest $contest, ContestProblem $contestProblem) {
             return $this->dj->getSamplesZipStreamedResponse($contestProblem);
         });
     }
@@ -96,17 +96,14 @@ public function sampleZipAction(int $probId): StreamedResponse
      *
      * Shared code between testcases, problem text and attachments.
      */
-    protected function getBinaryFile(int $probId, callable $response): StreamedResponse
+    protected function getBinaryFile(string $probId, callable $response): StreamedResponse
     {
         $user    = $this->dj->getUser();
         $contest = $this->dj->getCurrentContest($user->getTeam()->getTeamid());
         if (!$contest || !$contest->getFreezeData()->started()) {
             throw new NotFoundHttpException(sprintf('Problem p%d not found or not available', $probId));
         }
-        $contestProblem = $this->em->getRepository(ContestProblem::class)->find([
-            'problem' => $probId,
-            'contest' => $contest,
-        ]);
+        $contestProblem = $this->em->getRepository(ContestProblem::class)->findByProblemAndContest($contest, $probId);
         if (!$contestProblem) {
             throw new NotFoundHttpException(sprintf('Problem p%d not found or not available', $probId));
         }
diff --git a/webapp/src/Controller/Team/ScoreboardController.php b/webapp/src/Controller/Team/ScoreboardController.php
index 069e5db60c..ca90b607b0 100644
--- a/webapp/src/Controller/Team/ScoreboardController.php
+++ b/webapp/src/Controller/Team/ScoreboardController.php
@@ -59,16 +59,15 @@ public function scoreboardAction(Request $request): Response
         return $this->render('team/scoreboard.html.twig', $data, $response);
     }
 
-    #[Route(path: '/team/{teamId<\d+>}', name: 'team_team')]
-    public function teamAction(Request $request, int $teamId): Response
+    #[Route(path: '/team/{teamId}', name: 'team_team')]
+    public function teamAction(Request $request, string $teamId): Response
     {
         if (!$this->config->get('enable_ranking')) {
             throw new BadRequestHttpException('Scoreboard is not available.');
         }
 
-        /** @var Team|null $team */
-        $team             = $this->em->getRepository(Team::class)->find($teamId);
-        if ($team && $team->getCategory() && !$team->getCategory()->getVisible() && $teamId !== $this->dj->getUser()->getTeamId()) {
+        $team = $this->em->getRepository(Team::class)->findByExternalId($teamId);
+        if ($team && $team->getCategory() && !$team->getCategory()->getVisible() && $teamId !== $this->dj->getUser()->getTeam()->getExternalid()) {
             $team = null;
         }
         $showFlags        = (bool)$this->config->get('show_flags');
diff --git a/webapp/src/DataFixtures/DefaultData/LanguageFixture.php b/webapp/src/DataFixtures/DefaultData/LanguageFixture.php
index 6c82704e40..302d9153a4 100644
--- a/webapp/src/DataFixtures/DefaultData/LanguageFixture.php
+++ b/webapp/src/DataFixtures/DefaultData/LanguageFixture.php
@@ -23,66 +23,65 @@ public function __construct(
     public function load(ObjectManager $manager): void
     {
         $data = [
-            // ID      external ID   name           extensions                 require  entry point   allow   allow   time   compile              compiler version      runner version
-            //                                                             entry point  description   submit  judge   factor script               command               command
-            ['adb',    'ada',        'Ada',         ['adb', 'ads'],              false, null,         false,  true,   1,     'adb',               'gnatmake --version', ''],
-            ['awk',    'awk',        'AWK',         ['awk'],                     false, null,         false,  true,   1,     'awk',               'awk --version',      'awk --version'],
-            ['bash',   'bash',       'Bash shell',  ['bash'],                    false, 'Main file',  false,  true,   1,     'bash',              'bash --version',     'bash --version'],
-            ['c',      'c',          'C',           ['c'],                       false, null,         true,   true,   1,     'c',                 'gcc --version',      ''],
-            ['cpp',    'cpp',        'C++',         ['cpp', 'cc', 'cxx', 'c++'], false, null,         true,   true,   1,     'cpp',               'g++ --version',      ''],
-            ['csharp', 'csharp',     'C#',          ['csharp', 'cs'],            false, null,         false,  true,   1,     'csharp',            'mcs --version',      'mono --version'],
-            ['f95',    'f95',        'Fortran',     ['f95', 'f90'],              false, null,         false,  true,   1,     'f95',               'gfortran --version', ''],
-            ['hs',     'haskell',    'Haskell',     ['hs', 'lhs'],               false, null,         false,  true,   1,     'hs',                'ghc --version',      ''],
-            ['java',   'java',       'Java',        ['java'],                    false, 'Main class', true,   true,   1,     'java_javac_detect', 'javac -version',     'java -version'],
-            ['js',     'javascript', 'JavaScript',  ['js', 'mjs'],               false, 'Main file',  false,  true,   1,     'js',                'nodejs --version',   'nodejs --version'],
-            ['lua',    'lua',        'Lua',         ['lua'],                     false, null,         false,  true,   1,     'lua',               'luac -v',            'lua -v'],
-            ['kt',     'kotlin',     'Kotlin',      ['kt'],                      true,  'Main class', false,  true,   1,     'kt',                'kotlinc -version',   'kotlin -version'],
-            ['pas',    'pascal',     'Pascal',      ['pas', 'p'],                false, 'Main file',  false,  true,   1,     'pas',               'fpc -iW',            ''],
-            ['pl',     'pl',         'Perl',        ['pl'],                      false, 'Main file',  false,  true,   1,     'pl',                'perl -v',            'perl -v'],
-            ['plg',    'prolog',     'Prolog',      ['plg'],                     false, 'Main file',  false,  true,   1,     'plg',               'swipl --version',    ''],
-            ['py3',    'python3',    'Python 3',    ['py'],                      false, 'Main file',  true,   true,   1,     'py3',               'pypy3 --version',    'pypy3 --version'],
-            ['ocaml',  'ocaml',      'OCaml',       ['ml'],                      false, null,         false,  true,   1,     'ocaml',             'ocamlopt --version', ''],
-            ['r',      'r',          'R',           ['R'],                       false, 'Main file',  false,  true,   1,     'r',                 'Rscript --version',  'Rscript --version'],
-            ['rb',     'ruby',       'Ruby',        ['rb'],                      false, 'Main file',  false,  true,   1,     'rb',                'ruby --version',     'ruby --version'],
-            ['rs',     'rust',       'Rust',        ['rs'],                      false, null,         false,  true,   1,     'rs',                'rustc --version',    ''],
-            ['scala',  'scala',      'Scala',       ['scala'],                   false, null,         false,  true,   1,     'scala',             'scalac -version',    'scala -version'],
-            ['sh',     'sh',         'POSIX shell', ['sh'],                      false, 'Main file',  false,  true,   1,     'sh',                'md5sum /bin/sh',                   'md5sum /bin/sh'],
-            ['swift',  'swift',      'Swift',       ['swift'],                   false, 'Main file',  false,  true,   1,     'swift',             'swiftc --version',   ''],
+            // external ID   name           extensions                 require  entry point   allow   allow   time   compile              compiler version      runner version
+            //                                                     entry point  description   submit  judge   factor script               command               command
+            ['ada',        'Ada',         ['adb', 'ads'],              false, null,         false,  true,   1,     'adb',               'gnatmake --version', ''],
+            ['awk',        'AWK',         ['awk'],                     false, null,         false,  true,   1,     'awk',               'awk --version',      'awk --version'],
+            ['bash',       'Bash shell',  ['bash'],                    false, 'Main file',  false,  true,   1,     'bash',              'bash --version',     'bash --version'],
+            ['c',          'C',           ['c'],                       false, null,         true,   true,   1,     'c',                 'gcc --version',      ''],
+            ['cpp',        'C++',         ['cpp', 'cc', 'cxx', 'c++'], false, null,         true,   true,   1,     'cpp',               'g++ --version',      ''],
+            ['csharp',     'C#',          ['csharp', 'cs'],            false, null,         false,  true,   1,     'csharp',            'mcs --version',      'mono --version'],
+            ['f95',        'Fortran',     ['f95', 'f90'],              false, null,         false,  true,   1,     'f95',               'gfortran --version', ''],
+            ['haskell',    'Haskell',     ['hs', 'lhs'],               false, null,         false,  true,   1,     'hs',                'ghc --version',      ''],
+            ['java',       'Java',        ['java'],                    false, 'Main class', true,   true,   1,     'java_javac_detect', 'javac -version',     'java -version'],
+            ['javascript', 'JavaScript',  ['js', 'mjs'],               false, 'Main file',  false,  true,   1,     'js',                'nodejs --version',   'nodejs --version'],
+            ['lua',        'Lua',         ['lua'],                     false, null,         false,  true,   1,     'lua',               'luac -v',            'lua -v'],
+            ['kotlin',     'Kotlin',      ['kt'],                      true,  'Main class', false,  true,   1,     'kt',                'kotlinc -version',   'kotlin -version'],
+            ['pascal',     'Pascal',      ['pas', 'p'],                false, 'Main file',  false,  true,   1,     'pas',               'fpc -iW',            ''],
+            ['pl',         'Perl',        ['pl'],                      false, 'Main file',  false,  true,   1,     'pl',                'perl -v',            'perl -v'],
+            ['prolog',     'Prolog',      ['plg'],                     false, 'Main file',  false,  true,   1,     'plg',               'swipl --version',    ''],
+            ['python3',    'Python 3',    ['py'],                      false, 'Main file',  true,   true,   1,     'py3',               'pypy3 --version',    'pypy3 --version'],
+            ['ocaml',      'OCaml',       ['ml'],                      false, null,         false,  true,   1,     'ocaml',             'ocamlopt --version', ''],
+            ['r',          'R',           ['R'],                       false, 'Main file',  false,  true,   1,     'r',                 'Rscript --version',  'Rscript --version'],
+            ['ruby',       'Ruby',        ['rb'],                      false, 'Main file',  false,  true,   1,     'rb',                'ruby --version',     'ruby --version'],
+            ['rust',       'Rust',        ['rs'],                      false, null,         false,  true,   1,     'rs',                'rustc --version',    ''],
+            ['scala',      'Scala',       ['scala'],                   false, null,         false,  true,   1,     'scala',             'scalac -version',    'scala -version'],
+            ['sh',         'POSIX shell', ['sh'],                      false, 'Main file',  false,  true,   1,     'sh',                'md5sum /bin/sh',                   'md5sum /bin/sh'],
+            ['swift',      'Swift',       ['swift'],                   false, 'Main file',  false,  true,   1,     'swift',             'swiftc --version',   ''],
         ];
 
         foreach ($data as $item) {
             // Note: we only create the language if it doesn't exist yet.
             // If it does, we will not update the data
-            if (!$manager->getRepository(Language::class)->find($item[0])) {
+            if (!$manager->getRepository(Language::class)->findOneBy(['externalid' => $item[0]])) {
                 $file = sprintf('%s/files/defaultdata/%s.zip',
-                    $this->sqlDir, $item[9]
+                    $this->sqlDir, $item[8]
                 );
-                if (!($executable = $manager->getRepository(Executable::class)->find($item[9]))) {
+                if (!($executable = $manager->getRepository(Executable::class)->find($item[8]))) {
                     $executable = (new Executable())
-                        ->setExecid($item[9])
-                        ->setDescription($item[9])
+                        ->setExecid($item[8])
+                        ->setDescription($item[8])
                         ->setType('compile')
                         ->setImmutableExecutable($this->createImmutableExecutable($file));
                     $manager->persist($executable);
                 } else {
-                    $this->logger->info('Executable %s already exists, not created', [ $item[9] ]);
+                    $this->logger->info('Executable %s already exists, not created', [ $item[8] ]);
                 }
                 $language = (new Language())
-                    ->setLangid($item[0])
-                    ->setExternalid($item[1])
-                    ->setName($item[2])
-                    ->setExtensions($item[3])
-                    ->setRequireEntryPoint($item[4])
-                    ->setEntryPointDescription($item[5])
-                    ->setAllowSubmit($item[6])
-                    ->setAllowJudge($item[7])
-                    ->setTimeFactor($item[8])
+                    ->setExternalid($item[0])
+                    ->setName($item[1])
+                    ->setExtensions($item[2])
+                    ->setRequireEntryPoint($item[3])
+                    ->setEntryPointDescription($item[4])
+                    ->setAllowSubmit($item[5])
+                    ->setAllowJudge($item[6])
+                    ->setTimeFactor($item[7])
                     ->setCompileExecutable($executable);
-                if (!empty($item[10])) {
-                    $language->setCompilerVersionCommand($item[10]);
+                if (!empty($item[9])) {
+                    $language->setCompilerVersionCommand($item[9]);
                 }
-                if (!empty($item[11])) {
-                    $language->setRunnerVersionCommand($item[11]);
+                if (!empty($item[10])) {
+                    $language->setRunnerVersionCommand($item[10]);
                 }
                 $manager->persist($language);
             } else {
diff --git a/webapp/src/DataFixtures/Test/BalloonCorrectSubmissionFixture.php b/webapp/src/DataFixtures/Test/BalloonCorrectSubmissionFixture.php
index beadaa8f99..29ab0b98da 100644
--- a/webapp/src/DataFixtures/Test/BalloonCorrectSubmissionFixture.php
+++ b/webapp/src/DataFixtures/Test/BalloonCorrectSubmissionFixture.php
@@ -45,7 +45,7 @@ public function load(ObjectManager $manager): void
                 ->setContest($contest)
                 ->setTeam($team)
                 ->setContestProblem($cp)
-                ->setLanguage($manager->getRepository(Language::class)->find($submissionItem[1]))
+                ->setLanguage($manager->getRepository(Language::class)->findByExternalId($submissionItem[1]))
                 ->setSubmittime(Utils::now()-2)
                 ->setEntryPoint($submissionItem[3]);
             $judging = (new Judging())
diff --git a/webapp/src/DataFixtures/Test/EnableJavaEntrypointFixture.php b/webapp/src/DataFixtures/Test/EnableJavaEntrypointFixture.php
index 43875e1a1e..285390ad3f 100644
--- a/webapp/src/DataFixtures/Test/EnableJavaEntrypointFixture.php
+++ b/webapp/src/DataFixtures/Test/EnableJavaEntrypointFixture.php
@@ -9,7 +9,7 @@ class EnableJavaEntrypointFixture extends AbstractTestDataFixture
 {
     public function load(ObjectManager $manager): void
     {
-        $java = $manager->getRepository(Language::class)->find('java');
+        $java = $manager->getRepository(Language::class)->findByExternalId('java');
         $java->setRequireEntryPoint(true);
         $manager->flush();
     }
diff --git a/webapp/src/DataFixtures/Test/EnableKotlinFixture.php b/webapp/src/DataFixtures/Test/EnableKotlinFixture.php
index 02b0b4dcfd..6d05423696 100644
--- a/webapp/src/DataFixtures/Test/EnableKotlinFixture.php
+++ b/webapp/src/DataFixtures/Test/EnableKotlinFixture.php
@@ -9,7 +9,7 @@ class EnableKotlinFixture extends AbstractTestDataFixture
 {
     public function load(ObjectManager $manager): void
     {
-        $kotlin = $manager->getRepository(Language::class)->find('kt');
+        $kotlin = $manager->getRepository(Language::class)->findByExternalId('kotlin');
         $kotlin->setAllowSubmit(true);
         $manager->flush();
     }
diff --git a/webapp/src/DataFixtures/Test/RejudgingFirstToSolveFixture.php b/webapp/src/DataFixtures/Test/RejudgingFirstToSolveFixture.php
index a5fb6c9f06..9d6a276891 100644
--- a/webapp/src/DataFixtures/Test/RejudgingFirstToSolveFixture.php
+++ b/webapp/src/DataFixtures/Test/RejudgingFirstToSolveFixture.php
@@ -32,7 +32,7 @@ public function load(ObjectManager $manager): void
             [$team1, $contest->getStarttime() + 400, 'correct'],
         ];
 
-        $language = $manager->getRepository(Language::class)->find('cpp');
+        $language = $manager->getRepository(Language::class)->findByExternalId('cpp');
         $problem = $contest->getProblems()->filter(fn(ContestProblem $problem) => $problem->getShortname() === 'A')->first();
 
         foreach ($submissionData as $submissionItem) {
diff --git a/webapp/src/DataFixtures/Test/RejudgingStatesFixture.php b/webapp/src/DataFixtures/Test/RejudgingStatesFixture.php
index fe7b893955..941653a555 100644
--- a/webapp/src/DataFixtures/Test/RejudgingStatesFixture.php
+++ b/webapp/src/DataFixtures/Test/RejudgingStatesFixture.php
@@ -50,7 +50,7 @@ public function load(ObjectManager $manager): void
                 /** @var Team $team */
                 $team = $manager->getRepository(Team::class)->findOneBy(['name' => 'Example teamname']);
                 /** @var Language $language */
-                $language = $manager->getRepository(Language::class)->find('java');
+                $language = $manager->getRepository(Language::class)->findByExternalId('java');
                 // A rejudging has both judgings todo and finished
                 for ($b = 0; $b<=1; $b++) {
                     for ($x = 0; $x < $rejudgingStage[2+$b]; $x++) {
diff --git a/webapp/src/DataFixtures/Test/SampleSubmissionsFixture.php b/webapp/src/DataFixtures/Test/SampleSubmissionsFixture.php
index 82b53c23b3..0cf902632e 100644
--- a/webapp/src/DataFixtures/Test/SampleSubmissionsFixture.php
+++ b/webapp/src/DataFixtures/Test/SampleSubmissionsFixture.php
@@ -31,7 +31,7 @@ public function load(ObjectManager $manager): void
                 ->setContest($contest)
                 ->setTeam($manager->getRepository(Team::class)->findOneBy(['name' => $submissionItem[0]]))
                 ->setContestProblem($problem)
-                ->setLanguage($manager->getRepository(Language::class)->find($submissionItem[2]))
+                ->setLanguage($manager->getRepository(Language::class)->findByExternalId($submissionItem[2]))
                 ->setSubmittime(Utils::toEpochFloat($submissionItem[3]))
                 ->setEntryPoint($submissionItem[4]);
             $judging = (new Judging())
diff --git a/webapp/src/DataFixtures/Test/SampleSubmissionsInBucketsFixture.php b/webapp/src/DataFixtures/Test/SampleSubmissionsInBucketsFixture.php
index 54314f8dad..0c7a354f5f 100644
--- a/webapp/src/DataFixtures/Test/SampleSubmissionsInBucketsFixture.php
+++ b/webapp/src/DataFixtures/Test/SampleSubmissionsInBucketsFixture.php
@@ -43,7 +43,7 @@ public function load(ObjectManager $manager): void
                 ->setContest($demoContest)
                 ->setTeam($manager->getRepository(Team::class)->findOneBy(['name' => 'Example teamname']))
                 ->setContestProblem($problem)
-                ->setLanguage($manager->getRepository(Language::class)->find('cpp'))
+                ->setLanguage($manager->getRepository(Language::class)->findByExternalId('cpp'))
                 ->setSubmittime(Utils::toEpochFloat($time));
             $judging    = (new Judging())
                 ->setContest($demoContest)
diff --git a/webapp/src/DataFixtures/Test/SampleSubmissionsMultipleTriesFixture.php b/webapp/src/DataFixtures/Test/SampleSubmissionsMultipleTriesFixture.php
index 987cbe70e5..162aec616d 100644
--- a/webapp/src/DataFixtures/Test/SampleSubmissionsMultipleTriesFixture.php
+++ b/webapp/src/DataFixtures/Test/SampleSubmissionsMultipleTriesFixture.php
@@ -17,10 +17,10 @@ public function load(ObjectManager $manager): void
     {
         $submissionData = [
             // team name,         problem shortname, language, submittime,            entry point, result
-            ['Example teamname',  'C',        'cpp',    '2021-02-01 01:00:56', null,        'timelimit'],
-            ['Example teamname',  'C',        'c',      '2021-02-01 03:15:56', null,        'run-error'],
-            ['Example teamname',  'C',        'java',   '2021-02-01 18:00:00', 'Main',      'wrong-answer'],
-            ['Example teamname',  'C',        'py3',    '2021-02-01 18:00:34', 'main',      'compiler-error'],
+            ['Example teamname',  'C',        'cpp',     '2021-02-01 01:00:56', null,        'timelimit'],
+            ['Example teamname',  'C',        'c',       '2021-02-01 03:15:56', null,        'run-error'],
+            ['Example teamname',  'C',        'java',    '2021-02-01 18:00:00', 'Main',      'wrong-answer'],
+            ['Example teamname',  'C',        'python3', '2021-02-01 18:00:34', 'main',      'compiler-error'],
         ];
 
         /** @var Contest $contest */
@@ -33,7 +33,7 @@ public function load(ObjectManager $manager): void
                 ->setContest($contest)
                 ->setTeam($manager->getRepository(Team::class)->findOneBy(['name' => $submissionItem[0]]))
                 ->setContestProblem($problem)
-                ->setLanguage($manager->getRepository(Language::class)->find($submissionItem[2]))
+                ->setLanguage($manager->getRepository(Language::class)->findByExternalId($submissionItem[2]))
                 ->setSubmittime(Utils::toEpochFloat($submissionItem[3]))
                 ->setEntryPoint($submissionItem[4]);
             $judging = (new Judging())
diff --git a/webapp/src/DataFixtures/Test/SampleSubmissionsThreeTriesCorrectFixture.php b/webapp/src/DataFixtures/Test/SampleSubmissionsThreeTriesCorrectFixture.php
index 326006a327..26046c489e 100644
--- a/webapp/src/DataFixtures/Test/SampleSubmissionsThreeTriesCorrectFixture.php
+++ b/webapp/src/DataFixtures/Test/SampleSubmissionsThreeTriesCorrectFixture.php
@@ -32,7 +32,7 @@ public function load(ObjectManager $manager): void
                 ->setContest($contest)
                 ->setTeam($manager->getRepository(Team::class)->findOneBy(['name' => $submissionItem[0]]))
                 ->setContestProblem($problem)
-                ->setLanguage($manager->getRepository(Language::class)->find($submissionItem[2]))
+                ->setLanguage($manager->getRepository(Language::class)->findByExternalId($submissionItem[2]))
                 ->setSubmittime(Utils::toEpochFloat($submissionItem[3]))
                 ->setEntryPoint($submissionItem[4]);
             $judging = (new Judging())
diff --git a/webapp/src/DataFixtures/Test/SampleSubmissionsThreeTriesCorrectSameLanguageFixture.php b/webapp/src/DataFixtures/Test/SampleSubmissionsThreeTriesCorrectSameLanguageFixture.php
index 4615861c42..5bc7c0dc5e 100644
--- a/webapp/src/DataFixtures/Test/SampleSubmissionsThreeTriesCorrectSameLanguageFixture.php
+++ b/webapp/src/DataFixtures/Test/SampleSubmissionsThreeTriesCorrectSameLanguageFixture.php
@@ -32,7 +32,7 @@ public function load(ObjectManager $manager): void
                 ->setContest($contest)
                 ->setTeam($manager->getRepository(Team::class)->findOneBy(['name' => $submissionItem[0]]))
                 ->setContestProblem($problem)
-                ->setLanguage($manager->getRepository(Language::class)->find($submissionItem[2]))
+                ->setLanguage($manager->getRepository(Language::class)->findByExternalId($submissionItem[2]))
                 ->setSubmittime(Utils::toEpochFloat($submissionItem[3]))
                 ->setEntryPoint($submissionItem[4]);
             $judging = (new Judging())
diff --git a/webapp/src/DataTransferObject/Balloon.php b/webapp/src/DataTransferObject/Balloon.php
index 8d8721eb7c..914e858e7e 100644
--- a/webapp/src/DataTransferObject/Balloon.php
+++ b/webapp/src/DataTransferObject/Balloon.php
@@ -16,12 +16,12 @@ public function __construct(
         public readonly string $problem,
         public readonly ContestProblem $contestproblem,
         public readonly string $team,
-        public readonly int $teamid,
+        public readonly string $teamid,
         public readonly ?string $location,
         public readonly ?string $affiliation,
-        public readonly ?int $affiliationid,
+        public readonly ?string $affiliationid,
         public readonly ?string $category,
-        public readonly ?int $categoryid,
+        public readonly ?string $categoryid,
         #[Serializer\Type('array<string, App\Entity\ContestProblem>')]
         public readonly array $total,
         public readonly bool $done,
diff --git a/webapp/src/DataTransferObject/SubmissionRestriction.php b/webapp/src/DataTransferObject/SubmissionRestriction.php
index c23f86bf4f..268348fd99 100644
--- a/webapp/src/DataTransferObject/SubmissionRestriction.php
+++ b/webapp/src/DataTransferObject/SubmissionRestriction.php
@@ -2,45 +2,51 @@
 
 namespace App\DataTransferObject;
 
+use App\DataTransferObject\Scoreboard\Problem;
+use App\Entity\Language;
+use App\Entity\Team;
+use App\Entity\TeamAffiliation;
+use App\Entity\TeamCategory;
+
 class SubmissionRestriction
 {
     /**
-     * @param int|null          $rejudgingId         ID of a rejudging to filter on
-     * @param bool|null         $verified            If true, only return verified submissions
-     *                                               If false, only return unverified or unjudged submissions
-     * @param bool|null         $judged              If true, only return judged submissions
-     *                                               If false, only return unjudged submissions
-     * @param bool|null         $judging             If true, only return submissions currently being judged
-     *                                               If false, only return submssions which are already judged or still
-     *                                               need to be judged
-     * @param bool|null         $rejudgingDifference If true, only return judgings that differ from their
-     *                                               original result in final verdict. Vice versa if false
-     * @param int|null          $teamId              ID of a team to filter on
-     * @param list<int>|null    $teamIds             ID's of teams to filter on
-     * @param int|null          $categoryId          ID of a category to filter on
-     * @param list<int>|null    $categoryIds         ID's of categories to filter on
-     * @param int|null          $affiliationId       ID of an affiliation to filter on
-     * @param list<int>|null    $affiliationIds      ID's of affiliations to filter on
-     * @param int|null          $problemId           ID of a problem to filter on
-     * @param list<int>|null    $problemIds          ID's of problems to filter on
-     * @param string|null       $languageId          ID of a language to filter on
-     * @param list<string>|null $languageIds         ID's of languages to filter on
-     * @param string|null       $judgehost           Hostname of a judgehost to filter on
-     * @param string|null       $oldResult           Result of old judging to filter on
-     * @param string|null       $result              Result of current judging to filter on
-     * @param list<string>|null $results             Results of current judging to filter on
-     * @param int|null          $userId              Filter on specific user
-     * @param bool|null         $visible             If true, only return submissions from visible teams
-     * @param bool|null         $externalDifference  If true, only return results with a difference with an
-     *                                               external system
-     *                                               If false, only return results without a difference with an
-     *                                               external system
-     * @param string|null       $externalResult      Result in the external system
-     * @param bool|null         $externallyJudged    If true, only return externally judged submissions
-     *                                               If false, only return externally unjudged submissions
-     * @param bool|null         $externallyVerified  If true, only return verified submissions
-     *                                               If false, only return unverified or unjudged submissions
-     * @param bool|null         $withExternalId      If true, only return submissions with an external ID.
+     * @param int|null                                $rejudgingId         ID of a rejudging to filter on
+     * @param bool|null                               $verified            If true, only return verified submissions
+     *                                                                     If false, only return unverified or unjudged submissions
+     * @param bool|null                               $judged              If true, only return judged submissions
+     *                                                                     If false, only return unjudged submissions
+     * @param bool|null                               $judging             If true, only return submissions currently being judged
+     *                                                                     If false, only return submssions which are already judged or still
+     *                                                                     need to be judged
+     * @param bool|null                               $rejudgingDifference If true, only return judgings that differ from their
+     *                                                                     original result in final verdict. Vice versa if false
+     * @param int|null                                $teamId              ID of a team to filter on
+     * @param list<int>|list<Team>|null               $teamIds             ID's of teams to filter on
+     * @param int|null                                $categoryId          ID of a category to filter on
+     * @param list<int>|list<TeamCategory>|null       $categoryIds         ID's of categories to filter on
+     * @param int|null                                $affiliationId       ID of an affiliation to filter on
+     * @param list<int>|list<TeamAffiliation>|null    $affiliationIds      ID's of affiliations to filter on
+     * @param int|null                                $problemId           ID of a problem to filter on
+     * @param list<int>|list<Problem>|null            $problemIds          ID's of problems to filter on
+     * @param int|null                                $languageId          ID of a language to filter on
+     * @param list<int>|list<Language>|null           $languageIds         ID's of languages to filter on
+     * @param string|null                             $judgehost           Hostname of a judgehost to filter on
+     * @param string|null                             $oldResult           Result of old judging to filter on
+     * @param string|null                             $result              Result of current judging to filter on
+     * @param list<string>|null                       $results             Results of current judging to filter on
+     * @param int|null                                $userId              Filter on specific user
+     * @param bool|null                               $visible             If true, only return submissions from visible teams
+     * @param bool|null                               $externalDifference  If true, only return results with a difference with an
+     *                                                                     external system
+     *                                                                     If false, only return results without a difference with an
+     *                                                                     external system
+     * @param string|null                             $externalResult      Result in the external system
+     * @param bool|null                               $externallyJudged    If true, only return externally judged submissions
+     *                                                                     If false, only return externally unjudged submissions
+     * @param bool|null                               $externallyVerified  If true, only return verified submissions
+     *                                                                     If false, only return unverified or unjudged submissions
+     * @param bool|null                               $withExternalId      If true, only return submissions with an external ID.
      */
     public function __construct(
         public ?int $rejudgingId = null,
@@ -56,7 +62,7 @@ public function __construct(
         public ?array $affiliationIds = [],
         public ?int $problemId = null,
         public ?array $problemIds = [],
-        public ?string $languageId = null,
+        public ?int $languageId = null,
         public ?array $languageIds = [],
         public ?string $judgehost = null,
         public ?string $oldResult = null,
diff --git a/webapp/src/Entity/AuditLog.php b/webapp/src/Entity/AuditLog.php
index 416620d9bf..922e556632 100644
--- a/webapp/src/Entity/AuditLog.php
+++ b/webapp/src/Entity/AuditLog.php
@@ -33,9 +33,9 @@ class AuditLog
 
     #[ORM\Column(
         nullable: true,
-        options: ['comment' => 'Contest ID associated to this entry', 'unsigned' => true]
+        options: ['comment' => 'External contest ID associated to this entry', 'unsigned' => true]
     )]
-    private ?int $cid = null;
+    private ?string $cid = null;
 
     #[ORM\Column(
         nullable: true,
@@ -52,7 +52,7 @@ class AuditLog
     #[ORM\Column(
         length: 64,
         nullable: true,
-        options: ['comment' => 'Identifier in reference table']
+        options: ['comment' => '(External) identifier in reference table']
     )]
     private ?string $dataid = null;
 
@@ -81,13 +81,13 @@ public function getLogtime(): string|float
         return $this->logtime;
     }
 
-    public function setCid(?int $cid): AuditLog
+    public function setCid(?string $cid): AuditLog
     {
         $this->cid = $cid;
         return $this;
     }
 
-    public function getCid(): ?int
+    public function getCid(): ?string
     {
         return $this->cid;
     }
diff --git a/webapp/src/Entity/Clarification.php b/webapp/src/Entity/Clarification.php
index 05c4fb0628..23b793cd68 100644
--- a/webapp/src/Entity/Clarification.php
+++ b/webapp/src/Entity/Clarification.php
@@ -2,6 +2,7 @@
 namespace App\Entity;
 
 use App\Controller\API\AbstractRestController as ARC;
+use App\Repository\ClarificationRepository;
 use App\Utils\Utils;
 use Doctrine\Common\Collections\ArrayCollection;
 use Doctrine\Common\Collections\Collection;
@@ -13,7 +14,7 @@
 /**
  * Clarification requests by teams and responses by the jury.
  */
-#[ORM\Entity]
+#[ORM\Entity(repositoryClass: ClarificationRepository::class)]
 #[ORM\Table(options: [
     'collation' => 'utf8mb4_unicode_ci',
     'charset' => 'utf8mb4',
@@ -39,8 +40,7 @@ class Clarification extends BaseApiEntity implements
     #[ORM\Id]
     #[ORM\GeneratedValue]
     #[ORM\Column(options: ['comment' => 'Clarification ID', 'unsigned' => true])]
-    #[Serializer\SerializedName('clarid')]
-    #[Serializer\Groups([ARC::GROUP_RESTRICTED_NONSTRICT])]
+    #[Serializer\Exclude]
     protected int $clarid;
 
     #[ORM\Column(
diff --git a/webapp/src/Entity/Contest.php b/webapp/src/Entity/Contest.php
index 75dd6c7b25..546842f123 100644
--- a/webapp/src/Entity/Contest.php
+++ b/webapp/src/Entity/Contest.php
@@ -6,6 +6,7 @@
 use App\DataTransferObject\ContestState;
 use App\DataTransferObject\FileWithName;
 use App\DataTransferObject\ImageFile;
+use App\Repository\ContestRepository;
 use App\Utils\FreezeData;
 use App\Utils\Utils;
 use App\Validator\Constraints\Identifier;
@@ -28,7 +29,7 @@
 /**
  * Contests that will be run with this install.
  */
-#[ORM\Entity]
+#[ORM\Entity(repositoryClass: ContestRepository::class)]
 #[ORM\Table(options: [
     'collation' => 'utf8mb4_unicode_ci',
     'charset' => 'utf8mb4',
@@ -56,7 +57,7 @@ class Contest extends BaseApiEntity implements
     #[ORM\Id]
     #[ORM\GeneratedValue]
     #[ORM\Column(options: ['comment' => 'Contest ID', 'unsigned' => true])]
-    #[Serializer\Groups([ARC::GROUP_NONSTRICT])]
+    #[Serializer\Exclude]
     protected ?int $cid = null;
 
     #[ORM\Column(
diff --git a/webapp/src/Entity/ContestProblem.php b/webapp/src/Entity/ContestProblem.php
index 21d02e6bfe..0b6554dc2d 100644
--- a/webapp/src/Entity/ContestProblem.php
+++ b/webapp/src/Entity/ContestProblem.php
@@ -2,6 +2,7 @@
 namespace App\Entity;
 
 use App\Controller\API\AbstractRestController as ARC;
+use App\Repository\ContestProblemRepository;
 use App\Service\DOMJudgeService as DJS;
 use App\Utils\Utils;
 use Doctrine\Common\Collections\ArrayCollection;
@@ -14,7 +15,7 @@
 /**
  * Many-to-Many mapping of contests and problems.
  */
-#[ORM\Entity]
+#[ORM\Entity(repositoryClass: ContestProblemRepository::class)]
 #[ORM\Table(
     name: 'contestproblem',
     options: [
@@ -26,11 +27,6 @@
 #[ORM\Index(columns: ['cid'], name: 'cid')]
 #[ORM\Index(columns: ['probid'], name: 'probid')]
 #[ORM\UniqueConstraint(name: 'shortname', columns: ['cid', 'shortname'], options: ['lengths' => [null, 190]])]
-#[Serializer\VirtualProperty(
-    name: 'probid',
-    exp: 'object.getProblem().getProbid()',
-    options: [new Serializer\Groups([ARC::GROUP_NONSTRICT])]
-)]
 
 #[Serializer\VirtualProperty(
     name: 'short_name',
diff --git a/webapp/src/Entity/JudgeTask.php b/webapp/src/Entity/JudgeTask.php
index 513efebee1..07168eee70 100644
--- a/webapp/src/Entity/JudgeTask.php
+++ b/webapp/src/Entity/JudgeTask.php
@@ -79,9 +79,9 @@ class JudgeTask
     #[Serializer\VirtualProperty]
     #[Serializer\SerializedName('submitid')]
     #[Serializer\Type('string')]
-    public function getSubmitid(): ?int
+    public function getSubmitid(): ?string
     {
-        return $this->submission?->getSubmitid();
+        return $this->submission?->getExternalid();
     }
 
 
diff --git a/webapp/src/Entity/Language.php b/webapp/src/Entity/Language.php
index ecaed5e89a..38e0bf1d30 100644
--- a/webapp/src/Entity/Language.php
+++ b/webapp/src/Entity/Language.php
@@ -3,7 +3,7 @@
 
 use App\Controller\API\AbstractRestController as ARC;
 use App\DataTransferObject\Command;
-use App\Validator\Constraints\Identifier;
+use App\Repository\LanguageRepository;
 use Doctrine\Common\Collections\ArrayCollection;
 use Doctrine\Common\Collections\Collection;
 use Doctrine\ORM\Mapping as ORM;
@@ -15,7 +15,7 @@
 /**
  * Programming languages in which teams can submit solutions.
  */
-#[ORM\Entity]
+#[ORM\Entity(repositoryClass: LanguageRepository::class)]
 #[ORM\Table(options: [
     'collation' => 'utf8mb4_unicode_ci',
     'charset' => 'utf8mb4',
@@ -30,12 +30,10 @@ class Language extends BaseApiEntity implements
     ExternalIdFromInternalIdInterface
 {
     #[ORM\Id]
-    #[ORM\Column(length: 32, options: ['comment' => 'Language ID (string)'])]
-    #[Assert\NotBlank]
-    #[Assert\NotEqualTo('add')]
-    #[Identifier]
+    #[ORM\GeneratedValue]
+    #[ORM\Column(options: ['comment' => 'Language ID', 'unsigned' => true])]
     #[Serializer\Exclude]
-    protected ?string $langid = null;
+    protected ?int $langid = null;
 
     #[ORM\Column(nullable: true, options: ['comment' => 'Language ID to expose in the REST API'])]
     #[Serializer\SerializedName('id')]
@@ -264,13 +262,13 @@ public function getRunnerData(): Command
         return $ret;
     }
 
-    public function setLangid(string $langid): Language
+    public function setLangid(int $langid): Language
     {
         $this->langid = $langid;
         return $this;
     }
 
-    public function getLangid(): ?string
+    public function getLangid(): ?int
     {
         return $this->langid;
     }
@@ -420,16 +418,11 @@ public function getSubmissions(): Collection
 
     public function getEditorLanguage(): string
     {
-        return match ($this->getLangid()) {
+        return match ($this->getExternalid()) {
             'bash' => 'shell',
-            'cxx' => 'cpp',
-            'kt' => 'kotlin',
-            'pas' => 'pascal',
             'pl' => 'perl',
-            'py2', 'py3' => 'python',
-            'rb' => 'ruby',
-            'rs' => 'rust',
-            default => $this->getLangid(),
+            'python2', 'python3' => 'python',
+            default => $this->getExternalid(),
         };
     }
 
diff --git a/webapp/src/Entity/Problem.php b/webapp/src/Entity/Problem.php
index a715cd9fdc..1dd8889607 100644
--- a/webapp/src/Entity/Problem.php
+++ b/webapp/src/Entity/Problem.php
@@ -3,6 +3,7 @@
 namespace App\Entity;
 
 use App\DataTransferObject\FileWithName;
+use App\Repository\ProblemRepository;
 use App\Utils\Utils;
 use Doctrine\Common\Collections\ArrayCollection;
 use Doctrine\Common\Collections\Collection;
@@ -18,7 +19,7 @@
 /**
  * Stores testcases per problem.
  */
-#[ORM\Entity]
+#[ORM\Entity(repositoryClass: ProblemRepository::class)]
 #[ORM\Table(options: [
     'collation' => 'utf8mb4_unicode_ci',
     'charset' => 'utf8mb4',
diff --git a/webapp/src/Entity/Submission.php b/webapp/src/Entity/Submission.php
index 0932fff1bd..1fcee2e8bd 100644
--- a/webapp/src/Entity/Submission.php
+++ b/webapp/src/Entity/Submission.php
@@ -4,6 +4,7 @@
 
 use App\Controller\API\AbstractRestController as ARC;
 use App\DataTransferObject\FileWithName;
+use App\Repository\SubmissionRepository;
 use App\Utils\Utils;
 use Doctrine\Common\Collections\ArrayCollection;
 use Doctrine\Common\Collections\Collection;
@@ -16,7 +17,7 @@
 /**
  * All incoming submissions.
  */
-#[ORM\Entity]
+#[ORM\Entity(repositoryClass: SubmissionRepository::class)]
 #[ORM\Table(options: [
     'collation' => 'utf8mb4_unicode_ci',
     'charset' => 'utf8mb4',
@@ -44,8 +45,7 @@ class Submission extends BaseApiEntity implements
     #[ORM\Id]
     #[ORM\GeneratedValue]
     #[ORM\Column(options: ['comment' => 'Submission ID', 'unsigned' => true])]
-    #[Serializer\SerializedName('submitid')]
-    #[Serializer\Groups([ARC::GROUP_NONSTRICT])]
+    #[Serializer\Exclude]
     protected int $submitid;
 
     #[ORM\Column(
diff --git a/webapp/src/Entity/Team.php b/webapp/src/Entity/Team.php
index fd9d4e4ef2..b6f73666b8 100644
--- a/webapp/src/Entity/Team.php
+++ b/webapp/src/Entity/Team.php
@@ -5,6 +5,7 @@
 use App\Controller\API\AbstractRestController as ARC;
 use App\DataTransferObject\ImageFile;
 use App\DataTransferObject\TeamLocation;
+use App\Repository\TeamRepository;
 use Doctrine\Common\Collections\ArrayCollection;
 use Doctrine\Common\Collections\Collection;
 use Doctrine\ORM\Mapping as ORM;
@@ -18,7 +19,7 @@
 /**
  * All teams participating in the contest.
  */
-#[ORM\Entity]
+#[ORM\Entity(repositoryClass: TeamRepository::class)]
 #[ORM\Table(options: ['collation' => 'utf8mb4_unicode_ci', 'charset' => 'utf8mb4'])]
 #[ORM\Index(columns: ['affilid'], name: 'affilid')]
 #[ORM\Index(columns: ['categoryid'], name: 'categoryid')]
@@ -38,8 +39,7 @@ class Team extends BaseApiEntity implements
     #[ORM\Id]
     #[ORM\GeneratedValue]
     #[ORM\Column(options: ['comment' => 'Team ID', 'unsigned' => true])]
-    #[Serializer\SerializedName('teamid')]
-    #[Serializer\Groups([ARC::GROUP_NONSTRICT])]
+    #[Serializer\Exclude]
     protected ?int $teamid = null;
 
     #[ORM\Column(
diff --git a/webapp/src/Entity/TeamAffiliation.php b/webapp/src/Entity/TeamAffiliation.php
index d77958d864..ba0ee2d1d7 100644
--- a/webapp/src/Entity/TeamAffiliation.php
+++ b/webapp/src/Entity/TeamAffiliation.php
@@ -3,6 +3,7 @@
 
 use App\Controller\API\AbstractRestController as ARC;
 use App\DataTransferObject\ImageFile;
+use App\Repository\TeamAffiliationRepository;
 use App\Validator\Constraints\Country;
 use Doctrine\Common\Collections\ArrayCollection;
 use Doctrine\Common\Collections\Collection;
@@ -16,7 +17,7 @@
 /**
  * Affilitations for teams (e.g.: university, company).
  */
-#[ORM\Entity]
+#[ORM\Entity(repositoryClass: TeamAffiliationRepository::class)]
 #[ORM\Table(options: [
     'collation' => 'utf8mb4_unicode_ci',
     'charset' => 'utf8mb4',
@@ -42,8 +43,7 @@ class TeamAffiliation extends BaseApiEntity implements
     #[ORM\Id]
     #[ORM\GeneratedValue]
     #[ORM\Column(options: ['comment' => 'Team affiliation ID', 'unsigned' => true])]
-    #[Serializer\SerializedName('affilid')]
-    #[Serializer\Groups([ARC::GROUP_NONSTRICT])]
+    #[Serializer\Exclude]
     protected ?int $affilid = null;
 
     #[ORM\Column(
diff --git a/webapp/src/Entity/TeamCategory.php b/webapp/src/Entity/TeamCategory.php
index 0ae161ff87..9a5829d150 100644
--- a/webapp/src/Entity/TeamCategory.php
+++ b/webapp/src/Entity/TeamCategory.php
@@ -2,6 +2,7 @@
 namespace App\Entity;
 
 use App\Controller\API\AbstractRestController as ARC;
+use App\Repository\TeamCategoryRepository;
 use Doctrine\Common\Collections\ArrayCollection;
 use Doctrine\Common\Collections\Collection;
 use Doctrine\ORM\Mapping as ORM;
@@ -14,7 +15,7 @@
 /**
  * Categories for teams (e.g.: participants, observers, ...).
  */
-#[ORM\Entity]
+#[ORM\Entity(repositoryClass: TeamCategoryRepository::class)]
 #[ORM\Table(options: [
     'collation' => 'utf8mb4_unicode_ci',
     'charset' => 'utf8mb4',
@@ -37,8 +38,7 @@ class TeamCategory extends BaseApiEntity implements
     #[ORM\Id]
     #[ORM\GeneratedValue]
     #[ORM\Column(options: ['comment' => 'Team category ID', 'unsigned' => true])]
-    #[Serializer\SerializedName('categoryid')]
-    #[Serializer\Groups([ARC::GROUP_NONSTRICT])]
+    #[Serializer\Exclude]
     protected ?int $categoryid = null;
 
     #[ORM\Column(
diff --git a/webapp/src/Entity/User.php b/webapp/src/Entity/User.php
index e829805659..01910a8f2c 100644
--- a/webapp/src/Entity/User.php
+++ b/webapp/src/Entity/User.php
@@ -2,6 +2,7 @@
 namespace App\Entity;
 
 use App\Controller\API\AbstractRestController as ARC;
+use App\Repository\UserRepository;
 use App\Utils\Utils;
 use DateTime;
 use Doctrine\Common\Collections\ArrayCollection;
@@ -18,7 +19,7 @@
 /**
  * Users that have access to DOMjudge.
  */
-#[ORM\Entity]
+#[ORM\Entity(repositoryClass: UserRepository::class)]
 #[ORM\Table(options: [
     'collation' => 'utf8mb4_unicode_ci',
     'charset' => 'utf8mb4',
@@ -38,8 +39,7 @@ class User extends BaseApiEntity implements
     #[ORM\Id]
     #[ORM\GeneratedValue]
     #[ORM\Column(options: ['comment' => 'User ID', 'unsigned' => true])]
-    #[Serializer\SerializedName('userid')]
-    #[Serializer\Groups([ARC::GROUP_NONSTRICT])]
+    #[Serializer\Exclude]
     private ?int $userid = null;
 
     #[ORM\Column(
@@ -214,7 +214,7 @@ public function getName(): ?string
 
     public function getShortDescription(): string
     {
-        return $this->getName();
+        return $this->getName() ?: $this->getUsername();
     }
 
     public function setEmail(?string $email): User
diff --git a/webapp/src/Form/Type/AbstractExternalIdEntityType.php b/webapp/src/Form/Type/AbstractExternalIdEntityType.php
index c79a8fbb92..2f934376f1 100644
--- a/webapp/src/Form/Type/AbstractExternalIdEntityType.php
+++ b/webapp/src/Form/Type/AbstractExternalIdEntityType.php
@@ -24,7 +24,7 @@ public function __construct(protected readonly EventLogService $eventLogService)
     protected function addExternalIdField(FormBuilderInterface $builder, string $entity): void
     {
         $builder->add('externalid', TextType::class, [
-            'label' => 'External ID',
+            'label' => 'ID',
             'help' => 'Leave empty to generate automatically.',
             'required' => false,
             'empty_data' => '',
diff --git a/webapp/src/Form/Type/ContestExportType.php b/webapp/src/Form/Type/ContestExportType.php
index 82fb3afbdb..fbc180fa79 100644
--- a/webapp/src/Form/Type/ContestExportType.php
+++ b/webapp/src/Form/Type/ContestExportType.php
@@ -14,8 +14,9 @@ public function buildForm(FormBuilderInterface $builder, array $options): void
     {
         $builder->add('contest', EntityType::class, [
             'class' => Contest::class,
+            'choice_value' => 'externalid',
             'choice_label' => fn(Contest $contest) => sprintf(
-                'c%d: %s - %s', $contest->getCid(), $contest->getShortname(), $contest->getName()
+                '%s: %s - %s', $contest->getExternalid(), $contest->getShortname(), $contest->getName()
             ),
         ]);
         $builder->add('export', SubmitType::class, ['icon' => 'fa-download']);
diff --git a/webapp/src/Form/Type/ContestProblemType.php b/webapp/src/Form/Type/ContestProblemType.php
index e3c89cdd1d..a191ef2f6e 100644
--- a/webapp/src/Form/Type/ContestProblemType.php
+++ b/webapp/src/Form/Type/ContestProblemType.php
@@ -21,7 +21,8 @@ public function buildForm(FormBuilderInterface $builder, array $options): void
         $builder->add('problem', EntityType::class, [
             'class' => Problem::class,
             'required' => true,
-            'choice_label' => fn(Problem $problem) => sprintf('p%d - %s', $problem->getProbid(), $problem->getName()),
+            'choice_label' => fn(Problem $problem) => sprintf('%s - %s', $problem->getExternalid(), $problem->getName()),
+            'choice_value' => 'externalid',
             'query_builder' => fn(EntityRepository $er) => $er
                 ->createQueryBuilder('p')
                 ->orderBy('p.probid'),
diff --git a/webapp/src/Form/Type/ContestType.php b/webapp/src/Form/Type/ContestType.php
index bcf1769bcc..419f4be719 100644
--- a/webapp/src/Form/Type/ContestType.php
+++ b/webapp/src/Form/Type/ContestType.php
@@ -124,6 +124,7 @@ public function buildForm(FormBuilderInterface $builder, array $options): void
             'class' => TeamCategory::class,
             'multiple' => true,
             'choice_label' => fn(TeamCategory $category) => $category->getName(),
+            'choice_value' => 'externalid',
             'help' => 'List of team categories that will receive medals for this contest.',
         ]);
         foreach (['gold', 'silver', 'bronze'] as $medalType) {
@@ -158,7 +159,8 @@ public function buildForm(FormBuilderInterface $builder, array $options): void
             'required' => false,
             'class' => Team::class,
             'multiple' => true,
-            'choice_label' => fn(Team $team) => sprintf('%s (t%d)', $team->getEffectiveName(), $team->getTeamid()),
+            'choice_label' => fn(Team $team) => sprintf('%s (%s)', $team->getEffectiveName(), $team->getExternalid()),
+            'choice_value' => 'externalid',
             'help' => 'List of teams participating in the contest, in case it is not open to all teams.',
         ]);
         $builder->add('teamCategories', EntityType::class, [
@@ -166,6 +168,7 @@ public function buildForm(FormBuilderInterface $builder, array $options): void
             'class' => TeamCategory::class,
             'multiple' => true,
             'choice_label' => fn(TeamCategory $category) => $category->getName(),
+            'choice_value' => 'externalid',
             'help' => 'List of team categories participating in the contest, in case it is not open to all teams.',
         ]);
         $builder->add('enabled', ChoiceType::class, [
@@ -215,6 +218,7 @@ public function buildForm(FormBuilderInterface $builder, array $options): void
             'class' => Language::class,
             'multiple' => true,
             'choice_label' => fn(Language $language) => sprintf('%s (%s)', $language->getName(), $language->getExternalid()),
+            'choice_value' => 'externalid',
             'help' => 'List of languages that can be used in this contest. Leave empty to allow all languages that are enabled globally.',
         ]);
 
diff --git a/webapp/src/Form/Type/JuryClarificationType.php b/webapp/src/Form/Type/JuryClarificationType.php
index 70b8a69689..6fe3a19633 100644
--- a/webapp/src/Form/Type/JuryClarificationType.php
+++ b/webapp/src/Form/Type/JuryClarificationType.php
@@ -22,7 +22,7 @@ class JuryClarificationType extends AbstractType
 {
     public const RECIPIENT_MUST_SELECT = 'domjudge-must-select';
 
-    /** @var int The clarification entity id if the entity exists in the database */
+    /** @var string The clarification entity id if the entity exists in the database */
     private $clarid;
 
     public function __construct(
@@ -41,12 +41,12 @@ public function buildForm(FormBuilderInterface $builder, array $options): void
 
         $limitToTeam = $options['limit_to_team'] ?? null;
         if ($limitToTeam) {
-            $recipientOptions[$this->getTeamLabel($limitToTeam)] = $limitToTeam->getTeamid();
+            $recipientOptions[$this->getTeamLabel($limitToTeam)] = $limitToTeam->getExternalid();
         } else {
             /** @var Team|null $limitToTeam */
             $teams = $this->dj->getTeamsForContest($this->dj->getCurrentContest());
             foreach ($teams as $team) {
-                $recipientOptions[$this->getTeamLabel($team)] = $team->getTeamid();
+                $recipientOptions[$this->getTeamLabel($team)] = $team->getExternalid();
             }
         }
 
@@ -57,7 +57,7 @@ public function buildForm(FormBuilderInterface $builder, array $options): void
         $contest = $this->dj->getCurrentContest();
         $hasCurrentContest = $contest !== null;
         if ($hasCurrentContest) {
-            $contests = [$contest->getCid() => $contest];
+            $contests = [$contest->getExternalid() => $contest];
         } else {
             $contests = $this->dj->getCurrentContests();
         }
@@ -82,14 +82,14 @@ public function buildForm(FormBuilderInterface $builder, array $options): void
                 };
             }
             foreach ($categories as $name => $desc) {
-                $subjectOptions["$namePrefix $desc"] = "$cid-$name";
+                $subjectOptions["$namePrefix $desc"] = "$cid#$name";
             }
 
             foreach ($contestproblems as $cp) {
-                if ($cp->getCid() != $cid) {
+                if ($cp->getContest()->getExternalid() != $cid) {
                     continue;
                 }
-                $subjectOptions[$namePrefix . $cp->getShortname() . ': ' . $cp->getProblem()->getName()] = "$cid-" . $cp->getProbid();
+                $subjectOptions[$namePrefix . $cp->getShortname() . ': ' . $cp->getProblem()->getName()] = "$cid|" . $cp->getProblem()->getExternalid();
             }
         }
 
@@ -141,7 +141,7 @@ public function checkJuryMember(mixed $value, ExecutionContextInterface $context
             $juryMember = $this->em->createQueryBuilder()
                 ->select('clar.jury_member')
                 ->from(Clarification::class, 'clar')
-                ->where('clar.clarid = :clarid')
+                ->where('clar.externalid = :clarid')
                 ->setParameter('clarid', $this->clarid)
                 ->getQuery()
                 ->getSingleResult()['jury_member'];
diff --git a/webapp/src/Form/Type/LanguageType.php b/webapp/src/Form/Type/LanguageType.php
index 2f0c70864f..55b733dd65 100644
--- a/webapp/src/Form/Type/LanguageType.php
+++ b/webapp/src/Form/Type/LanguageType.php
@@ -22,9 +22,6 @@ class LanguageType extends AbstractExternalIdEntityType
     public function buildForm(FormBuilderInterface $builder, array $options): void
     {
         $this->addExternalIdField($builder, Language::class);
-        $builder->add('langid', TextType::class, [
-            'label' => 'Language ID',
-        ]);
         $builder->add('name', TextType::class, [
             'empty_data' => ''
         ]);
diff --git a/webapp/src/Form/Type/PrintType.php b/webapp/src/Form/Type/PrintType.php
index a9ea10b54b..d8b852f8e2 100644
--- a/webapp/src/Form/Type/PrintType.php
+++ b/webapp/src/Form/Type/PrintType.php
@@ -21,7 +21,7 @@ public function buildForm(FormBuilderInterface $builder, array $options): void
         $languages       = $this->em->getRepository(Language::class)->findAll();
         $languageChoices = [];
         foreach ($languages as $language) {
-            $languageChoices[$language->getName()] = $language->getLangid();
+            $languageChoices[$language->getName()] = $language->getExternalid();
         }
         ksort($languageChoices, SORT_NATURAL | SORT_FLAG_CASE);
         $languageChoices = ['plain text' => ''] + $languageChoices;
diff --git a/webapp/src/Form/Type/ProblemType.php b/webapp/src/Form/Type/ProblemType.php
index 21f7959c79..ec39744da5 100644
--- a/webapp/src/Form/Type/ProblemType.php
+++ b/webapp/src/Form/Type/ProblemType.php
@@ -99,6 +99,7 @@ public function buildForm(FormBuilderInterface $builder, array $options): void
             'required' => false,
             'class' => Language::class,
             'multiple' => true,
+            'choice_value' => 'externalid',
             'choice_label' => fn(Language $language) => sprintf('%s (%s)', $language->getName(), $language->getExternalid()),
             'help' => 'List of languages that can be used for this problem. Leave empty to allow all languages that are enabled for this contest.',
         ]);
diff --git a/webapp/src/Form/Type/ProblemUploadType.php b/webapp/src/Form/Type/ProblemUploadType.php
index d704fea726..18d82ed1d1 100644
--- a/webapp/src/Form/Type/ProblemUploadType.php
+++ b/webapp/src/Form/Type/ProblemUploadType.php
@@ -17,8 +17,9 @@ public function buildForm(FormBuilderInterface $builder, array $options): void
             'class' => Contest::class,
             'required' => false,
             'placeholder' => 'Do not add / update contest data',
+            'choice_value' => 'externalid',
             'choice_label' => fn(Contest $contest) => sprintf(
-                'c%d: %s - %s', $contest->getCid(), $contest->getShortname(), $contest->getName()
+                '%s: %s - %s', $contest->getExternalid(), $contest->getShortname(), $contest->getName()
             ),
         ]);
         $builder->add('archive', FileType::class, [
diff --git a/webapp/src/Form/Type/ProblemsImportType.php b/webapp/src/Form/Type/ProblemsImportType.php
index 48aa01bc96..baedb1c147 100644
--- a/webapp/src/Form/Type/ProblemsImportType.php
+++ b/webapp/src/Form/Type/ProblemsImportType.php
@@ -16,8 +16,9 @@ public function buildForm(FormBuilderInterface $builder, array $options): void
         $builder->add('contest', EntityType::class, [
             'class' => Contest::class,
             'required' => true,
+            'choice_value' => 'externalid',
             'choice_label' => fn(Contest $contest) => sprintf(
-                'c%d: %s - %s', $contest->getCid(), $contest->getShortname(), $contest->getName()
+                '%s: %s - %s', $contest->getExternalid(), $contest->getShortname(), $contest->getName()
             ),
         ]);
         $builder->add('file', FileType::class, [
diff --git a/webapp/src/Form/Type/RejudgingType.php b/webapp/src/Form/Type/RejudgingType.php
index 5afcda07c6..96f453f0d8 100644
--- a/webapp/src/Form/Type/RejudgingType.php
+++ b/webapp/src/Form/Type/RejudgingType.php
@@ -53,6 +53,7 @@ public function buildForm(FormBuilderInterface $builder, array $options): void
             'required' => false,
             'multiple' => true,
             'choice_label' => 'name',
+            'choice_value' => 'externalid',
             'query_builder' => fn(EntityRepository $er) => $er
                 ->createQueryBuilder('c')
                 ->where('c.enabled = 1')
@@ -64,6 +65,7 @@ public function buildForm(FormBuilderInterface $builder, array $options): void
             'class' => Problem::class,
             'required' => false,
             'choice_label' => 'name',
+            'choice_value' => 'externalid',
             'choices' => [],
         ]);
         $builder->add('languages', EntityType::class, [
@@ -72,6 +74,7 @@ public function buildForm(FormBuilderInterface $builder, array $options): void
             'class' => Language::class,
             'required' => false,
             'choice_label' => 'name',
+            'choice_value' => 'externalid',
             'query_builder' => fn(EntityRepository $er) => $er
                 ->createQueryBuilder('l')
                 ->where('l.allowSubmit = 1')
@@ -83,6 +86,7 @@ public function buildForm(FormBuilderInterface $builder, array $options): void
             'class' => Team::class,
             'required' => false,
             'choice_label' => 'name',
+            'choice_value' => 'externalid',
             'choices' => [],
         ]);
         $builder->add('users', EntityType::class, [
@@ -91,6 +95,7 @@ public function buildForm(FormBuilderInterface $builder, array $options): void
             'required' => false,
             'multiple' => true,
             'choice_label' => 'name',
+            'choice_value' => 'externalid',
             'query_builder' => fn(EntityRepository $er) => $er
                 ->createQueryBuilder('u')
                 ->where('u.enabled = 1')
diff --git a/webapp/src/Form/Type/SubmissionsFilterType.php b/webapp/src/Form/Type/SubmissionsFilterType.php
index f962bb7501..ebb4ee439a 100644
--- a/webapp/src/Form/Type/SubmissionsFilterType.php
+++ b/webapp/src/Form/Type/SubmissionsFilterType.php
@@ -45,6 +45,7 @@ public function buildForm(FormBuilderInterface $builder, array $options): void
             "class" => Problem::class,
             "required" => false,
             "choice_label" => "name",
+            "choice_value" => "externalid",
             "choices" => $problems,
             "attr" => ["data-filter-field" => "problem-id"],
         ]);
@@ -54,6 +55,7 @@ public function buildForm(FormBuilderInterface $builder, array $options): void
             "class" => Language::class,
             "required" => false,
             "choice_label" => "name",
+            "choice_value" => "externalid",
             "query_builder" => fn(EntityRepository $er) => $er
                 ->createQueryBuilder("l")
                 ->where("l.allowSubmit = 1")
@@ -66,6 +68,7 @@ public function buildForm(FormBuilderInterface $builder, array $options): void
             "class" => TeamCategory::class,
             "required" => false,
             "choice_label" => "name",
+            "choice_value" => "externalid",
             "query_builder" => fn(EntityRepository $er) => $er
                 ->createQueryBuilder("tc")
                 ->orderBy("tc.name"),
@@ -77,6 +80,7 @@ public function buildForm(FormBuilderInterface $builder, array $options): void
             "class" => TeamAffiliation::class,
             "required" => false,
             "choice_label" => "name",
+            "choice_value" => "externalid",
             "query_builder" => fn(EntityRepository $er) => $er
                 ->createQueryBuilder("ta")
                 ->orderBy("ta.name"),
@@ -114,6 +118,7 @@ public function buildForm(FormBuilderInterface $builder, array $options): void
             "class" => Team::class,
             "required" => false,
             "choice_label" => "name",
+            "choice_value" => "externalid",
             "choices" => $teams,
             "attr" => ["data-filter-field" => "team-id"],
         ]);
diff --git a/webapp/src/Form/Type/SubmitProblemType.php b/webapp/src/Form/Type/SubmitProblemType.php
index 997bb21555..9532866b10 100644
--- a/webapp/src/Form/Type/SubmitProblemType.php
+++ b/webapp/src/Form/Type/SubmitProblemType.php
@@ -50,6 +50,7 @@ public function buildForm(FormBuilderInterface $builder, array $options): void
             'choice_label' => fn(Problem $problem) => sprintf(
                 '%s - %s', $problem->getContestProblems()->first()->getShortName(), $problem->getName()
             ),
+            'choice_value' => 'externalid',
             'placeholder' => 'Select a problem',
         ];
         $builder->add('problem', EntityType::class, $problemConfig);
@@ -59,6 +60,7 @@ public function buildForm(FormBuilderInterface $builder, array $options): void
             'class' => Language::class,
             'choices' => $languages,
             'choice_label' => 'name',
+            'choice_value' => 'externalid',
             'placeholder' => 'Select a language',
         ]);
 
diff --git a/webapp/src/Form/Type/TeamClarificationType.php b/webapp/src/Form/Type/TeamClarificationType.php
index 32dfcfe5af..babb3617ef 100644
--- a/webapp/src/Form/Type/TeamClarificationType.php
+++ b/webapp/src/Form/Type/TeamClarificationType.php
@@ -32,7 +32,7 @@ public function buildForm(FormBuilderInterface $builder, array $options): void
         $contest = $this->dj->getCurrentContest($user->getTeam()->getTeamid());
         if ($contest) {
             foreach ($categories as $categoryId => $categoryName) {
-                $subjects[$categoryName] = sprintf('%d-%s', $contest->getCid(), $categoryId);
+                $subjects[$categoryName] = sprintf('%s#%s', $contest->getExternalid(), $categoryId);
             }
             if ($contest->getFreezeData()->started()) {
                 /** @var ContestProblem $problem */
@@ -40,7 +40,7 @@ public function buildForm(FormBuilderInterface $builder, array $options): void
                     if ($problem->getAllowSubmit()) {
                         $problemName = sprintf('%s: %s', $problem->getShortname(),
                             $problem->getProblem()->getName());
-                        $subjects[$problemName] = sprintf('%d-%d', $contest->getCid(), $problem->getProbid());
+                        $subjects[$problemName] = sprintf('%s|%s', $contest->getExternalid(), $problem->getExternalId());
                     }
                 }
             }
diff --git a/webapp/src/Form/Type/TeamType.php b/webapp/src/Form/Type/TeamType.php
index 5a5cdde162..7ceb76a7bc 100644
--- a/webapp/src/Form/Type/TeamType.php
+++ b/webapp/src/Form/Type/TeamType.php
@@ -67,6 +67,7 @@ public function buildForm(FormBuilderInterface $builder, array $options): void
         ]);
         $builder->add('category', EntityType::class, [
             'class' => TeamCategory::class,
+            'choice_value' => 'externalid',
         ]);
         $builder->add('publicdescription', TextareaType::class, [
             'label' => 'Public description',
@@ -76,6 +77,7 @@ public function buildForm(FormBuilderInterface $builder, array $options): void
             'class'         => TeamAffiliation::class,
             'required'      => false,
             'choice_label'  => 'name',
+            'choice_value' => 'externalid',
             'placeholder'   => '-- no affiliation --',
             'query_builder' => fn(EntityRepository $er) => $er->createQueryBuilder('a')->orderBy('a.name'),
         ]);
@@ -97,6 +99,7 @@ public function buildForm(FormBuilderInterface $builder, array $options): void
             'class'         => Contest::class,
             'required'      => false,
             'choice_label'  => 'name',
+            'choice_value' => 'externalid',
             'multiple'      => true,
             'by_reference'  => false,
             'query_builder' => fn(EntityRepository $er) => $er
@@ -132,6 +135,7 @@ public function buildForm(FormBuilderInterface $builder, array $options): void
             'label'        => "User",
             'required'     => true,
             'choice_label' => 'name',
+            'choice_value' => 'externalid',
         ]);
         $builder->add('newUsername', TextType::class, [
             'label'    => 'Username',
diff --git a/webapp/src/Form/Type/UserType.php b/webapp/src/Form/Type/UserType.php
index 12da3e28c2..04acb1dbfa 100644
--- a/webapp/src/Form/Type/UserType.php
+++ b/webapp/src/Form/Type/UserType.php
@@ -78,6 +78,7 @@ public function buildForm(FormBuilderInterface $builder, array $options): void
             'choice_label' => 'effective_name',
             'required' => false,
             'placeholder' => '-- no team --',
+            'choice_value' => 'externalid',
             'choices' => $teams,
         ]);
         $builder->add('user_roles', EntityType::class, [
diff --git a/webapp/src/Repository/ClarificationRepository.php b/webapp/src/Repository/ClarificationRepository.php
new file mode 100644
index 0000000000..880c5b371f
--- /dev/null
+++ b/webapp/src/Repository/ClarificationRepository.php
@@ -0,0 +1,17 @@
+<?php declare(strict_types=1);
+
+namespace App\Repository;
+
+use App\Entity\Clarification;
+use Doctrine\ORM\EntityRepository;
+
+/**
+ * @extends EntityRepository<Clarification>
+ */
+class ClarificationRepository extends EntityRepository
+{
+    /**
+     * @use FindByExternalidTrait<Clarification>
+     */
+    use FindByExternalidTrait;
+}
diff --git a/webapp/src/Repository/ContestProblemRepository.php b/webapp/src/Repository/ContestProblemRepository.php
new file mode 100644
index 0000000000..72611eee1e
--- /dev/null
+++ b/webapp/src/Repository/ContestProblemRepository.php
@@ -0,0 +1,33 @@
+<?php declare(strict_types=1);
+
+namespace App\Repository;
+
+use App\Entity\Contest;
+use App\Entity\ContestProblem;
+use App\Entity\Problem;
+use Doctrine\ORM\EntityRepository;
+
+/**
+ * @extends EntityRepository<ContestProblem>
+ */
+class ContestProblemRepository extends EntityRepository
+{
+    public function findByProblemAndContest(Contest|string $contest, Problem|string $problem): ?ContestProblem
+    {
+        if ($contest instanceof Contest) {
+            $contest = $contest->getExternalid();
+        }
+        if ($problem instanceof Problem) {
+            $problem = $problem->getExternalid();
+        }
+        return $this->createQueryBuilder('cp')
+            ->innerJoin('cp.contest', 'c')
+            ->innerJoin('cp.problem', 'p')
+            ->andWhere('c.externalid = :contestId')
+            ->andWhere('p.externalid = :problemId')
+            ->setParameter('contestId', $contest)
+            ->setParameter('problemId', $problem)
+            ->getQuery()
+            ->getOneOrNullResult();
+    }
+}
diff --git a/webapp/src/Repository/ContestRepository.php b/webapp/src/Repository/ContestRepository.php
new file mode 100644
index 0000000000..cf564357fe
--- /dev/null
+++ b/webapp/src/Repository/ContestRepository.php
@@ -0,0 +1,17 @@
+<?php declare(strict_types=1);
+
+namespace App\Repository;
+
+use App\Entity\Contest;
+use Doctrine\ORM\EntityRepository;
+
+/**
+ * @extends EntityRepository<Contest>
+ */
+class ContestRepository extends EntityRepository
+{
+    /**
+     * @use FindByExternalidTrait<Contest>
+     */
+    use FindByExternalidTrait;
+}
diff --git a/webapp/src/Repository/FindByExternalidTrait.php b/webapp/src/Repository/FindByExternalidTrait.php
new file mode 100644
index 0000000000..ba4082ede0
--- /dev/null
+++ b/webapp/src/Repository/FindByExternalidTrait.php
@@ -0,0 +1,19 @@
+<?php declare(strict_types=1);
+
+namespace App\Repository;
+
+use App\Entity\HasExternalIdInterface as T;
+
+/**
+ * @template T of T
+ */
+trait FindByExternalidTrait
+{
+    /**
+     * @return T|null
+     */
+    public function findByExternalId(string $externalId): ?T
+    {
+        return $this->findOneBy(['externalid' => $externalId]);
+    }
+}
diff --git a/webapp/src/Repository/LanguageRepository.php b/webapp/src/Repository/LanguageRepository.php
new file mode 100644
index 0000000000..144a34601c
--- /dev/null
+++ b/webapp/src/Repository/LanguageRepository.php
@@ -0,0 +1,17 @@
+<?php declare(strict_types=1);
+
+namespace App\Repository;
+
+use App\Entity\Language;
+use Doctrine\ORM\EntityRepository;
+
+/**
+ * @extends EntityRepository<Language>
+ */
+class LanguageRepository extends EntityRepository
+{
+    /**
+     * @use FindByExternalidTrait<Language>
+     */
+    use FindByExternalidTrait;
+}
diff --git a/webapp/src/Repository/ProblemRepository.php b/webapp/src/Repository/ProblemRepository.php
new file mode 100644
index 0000000000..0a1d5131d0
--- /dev/null
+++ b/webapp/src/Repository/ProblemRepository.php
@@ -0,0 +1,17 @@
+<?php declare(strict_types=1);
+
+namespace App\Repository;
+
+use App\Entity\Problem;
+use Doctrine\ORM\EntityRepository;
+
+/**
+ * @extends EntityRepository<Problem>
+ */
+class ProblemRepository extends EntityRepository
+{
+    /**
+     * @use FindByExternalidTrait<Problem>
+     */
+    use FindByExternalidTrait;
+}
diff --git a/webapp/src/Repository/SubmissionRepository.php b/webapp/src/Repository/SubmissionRepository.php
new file mode 100644
index 0000000000..9e5facfef8
--- /dev/null
+++ b/webapp/src/Repository/SubmissionRepository.php
@@ -0,0 +1,17 @@
+<?php declare(strict_types=1);
+
+namespace App\Repository;
+
+use App\Entity\Submission;
+use Doctrine\ORM\EntityRepository;
+
+/**
+ * @extends EntityRepository<Submission>
+ */
+class SubmissionRepository extends EntityRepository
+{
+    /**
+     * @use FindByExternalidTrait<Submission>
+     */
+    use FindByExternalidTrait;
+}
diff --git a/webapp/src/Repository/TeamAffiliationRepository.php b/webapp/src/Repository/TeamAffiliationRepository.php
new file mode 100644
index 0000000000..14d283d35c
--- /dev/null
+++ b/webapp/src/Repository/TeamAffiliationRepository.php
@@ -0,0 +1,17 @@
+<?php declare(strict_types=1);
+
+namespace App\Repository;
+
+use App\Entity\TeamAffiliation;
+use Doctrine\ORM\EntityRepository;
+
+/**
+ * @extends EntityRepository<TeamAffiliation>
+ */
+class TeamAffiliationRepository extends EntityRepository
+{
+    /**
+     * @use FindByExternalidTrait<TeamAffiliation>
+     */
+    use FindByExternalidTrait;
+}
diff --git a/webapp/src/Repository/TeamCategoryRepository.php b/webapp/src/Repository/TeamCategoryRepository.php
new file mode 100644
index 0000000000..8780ced1fa
--- /dev/null
+++ b/webapp/src/Repository/TeamCategoryRepository.php
@@ -0,0 +1,17 @@
+<?php declare(strict_types=1);
+
+namespace App\Repository;
+
+use App\Entity\TeamCategory;
+use Doctrine\ORM\EntityRepository;
+
+/**
+ * @extends EntityRepository<TeamCategory>
+ */
+class TeamCategoryRepository extends EntityRepository
+{
+    /**
+     * @use FindByExternalidTrait<TeamCategory>
+     */
+    use FindByExternalidTrait;
+}
diff --git a/webapp/src/Repository/TeamRepository.php b/webapp/src/Repository/TeamRepository.php
new file mode 100644
index 0000000000..4c0f46de49
--- /dev/null
+++ b/webapp/src/Repository/TeamRepository.php
@@ -0,0 +1,17 @@
+<?php declare(strict_types=1);
+
+namespace App\Repository;
+
+use App\Entity\Team;
+use Doctrine\ORM\EntityRepository;
+
+/**
+ * @extends EntityRepository<Team>
+ */
+class TeamRepository extends EntityRepository
+{
+    /**
+     * @use FindByExternalidTrait<Team>
+     */
+    use FindByExternalidTrait;
+}
diff --git a/webapp/src/Repository/UserRepository.php b/webapp/src/Repository/UserRepository.php
new file mode 100644
index 0000000000..5ddde5aefd
--- /dev/null
+++ b/webapp/src/Repository/UserRepository.php
@@ -0,0 +1,17 @@
+<?php declare(strict_types=1);
+
+namespace App\Repository;
+
+use App\Entity\User;
+use Doctrine\ORM\EntityRepository;
+
+/**
+ * @extends EntityRepository<User>
+ */
+class UserRepository extends EntityRepository
+{
+    /**
+     * @use FindByExternalidTrait<User>
+     */
+    use FindByExternalidTrait;
+}
diff --git a/webapp/src/Security/UserStateUpdater.php b/webapp/src/Security/UserStateUpdater.php
index 981e9e079b..89ab53eaa5 100644
--- a/webapp/src/Security/UserStateUpdater.php
+++ b/webapp/src/Security/UserStateUpdater.php
@@ -47,7 +47,7 @@ public function updateUserState(AuthenticationSuccessEvent $event): void
             // Otherwise, we would log every API call and we do not want that.
             if ($firewallName === 'main') {
                 $ip = $this->requestStack->getMainRequest()->getClientIp();
-                $this->dj->auditlog('user', $user->getUserid(), 'logged on on ' . $ip, null, $user->getUserName());
+                $this->dj->auditlog('user', $user->getExternalid(), 'logged on on ' . $ip, null, $user->getUserName());
             }
         }
     }
diff --git a/webapp/src/Service/BalloonService.php b/webapp/src/Service/BalloonService.php
index eb80ffe0f7..e245c0b5c9 100644
--- a/webapp/src/Service/BalloonService.php
+++ b/webapp/src/Service/BalloonService.php
@@ -85,8 +85,8 @@ public function updateBalloons(
 
     /**
      * @return array<array{data: array{balloonid: int, time: string, problem: string, contestproblem: ContestProblem,
-     *                                 team: Team, teamid: int, location: string|null, affiliation: string|null,
-     *                                 affiliationid: int, category: string, categoryid: int, total: array<string, ContestProblem>,
+     *                                 team: Team, teamid: string, location: string|null, affiliation: string|null,
+     *                                 affiliationid: string, category: string, categoryid: string, total: array<string, ContestProblem>,
      *                                 done: bool}}>
     */
     public function collectBalloonTable(Contest $contest, bool $todo = false): array
@@ -99,11 +99,11 @@ public function collectBalloonTable(Contest $contest, bool $todo = false): array
 
         $query = $em->createQueryBuilder()
             ->select('b', 's.submittime', 'p.probid',
-                't.teamid', 's', 't', 't.location',
-                'c.categoryid AS categoryid', 'c.name AS catname',
-                'co.cid', 'co.shortname',
+                't.externalid as teamid', 's', 't', 't.location',
+                'c.externalid AS categoryid', 'c.name AS catname',
+                'co.externalid as cid', 'co.shortname',
                 'cp.shortname AS probshortname', 'cp.color',
-                'a.affilid AS affilid', 'a.shortname AS affilshort')
+                'a.externalid AS affilid', 'a.shortname AS affilshort')
             ->from(Balloon::class, 'b')
             ->leftJoin('b.submission', 's')
             ->leftJoin('b.problem', 'p')
diff --git a/webapp/src/Service/CheckConfigService.php b/webapp/src/Service/CheckConfigService.php
index 5f1c76f4b3..e722c0fa1f 100644
--- a/webapp/src/Service/CheckConfigService.php
+++ b/webapp/src/Service/CheckConfigService.php
@@ -107,8 +107,8 @@ public function runAll(): array
         $this->stopwatch->stopSection('Teams');
 
         $this->stopwatch->openSection();
-        $results['External identifiers'] = $this->checkAllExternalIdentifiers();
-        $this->stopwatch->stopSection('External identifiers');
+        $results['Identifiers'] = $this->checkAllExternalIdentifiers();
+        $this->stopwatch->stopSection('Identifiers');
 
         return $results;
     }
@@ -491,7 +491,7 @@ public function checkContestActive(): ConfigCheckItem
         $this->stopwatch->stop(__FUNCTION__);
         $desc = '';
         foreach ($contests as $contest) {
-            $desc .= '  - c' . $contest->getCid() . ' (' . $contest->getShortname() . ")\n";
+            $desc .= '  - `' . $contest->getExternalid() . '` (' . $contest->getShortname() . ")\n";
         }
         return new ConfigCheckItem(
             caption: 'Active contests',
@@ -509,7 +509,7 @@ public function checkContestsValidate(): ConfigCheckItem
         $contesterrors = $cperrors = [];
         $result = 'O';
         foreach ($contests as $contest) {
-            $cid = $contest->getCid();
+            $cid = $contest->getExternalid();
             $errors = $this->validator->validate($contest);
             if (count($errors)) {
                 $result = 'E';
@@ -527,7 +527,7 @@ public function checkContestsValidate(): ConfigCheckItem
 
         $desc = '';
         foreach ($contesterrors as $cid => $errors) {
-            $desc .= "Contest: c$cid: ";
+            $desc .= "Contest: `$cid`: ";
             if (count($errors) == 0 && empty($cperrors[$cid])) {
                 $desc .= "no errors\n";
             } else {
@@ -559,7 +559,7 @@ public function checkContestBanners(): ConfigCheckItem
         foreach ($contests as $contest) {
             if ($cid = $contest->getExternalid()) {
                 $bannerpath = $this->dj->assetPath($cid, 'contest', true);
-                $contestName = 'c' . $contest->getCid() . ' (' . $contest->getShortname() . ')';
+                $contestName = $contest->getExternalid() . ' (' . $contest->getShortname() . ')';
                 if ($bannerpath) {
                     if (($filesize = filesize($bannerpath)) > 2 * 1024 * 1024) {
                         $result = 'W';
@@ -598,7 +598,7 @@ public function checkProblemsValidate(): ConfigCheckItem
         $problemerrors = $moreproblemerrors = [];
         $result = 'O';
         foreach ($problems as $problem) {
-            $probid = $problem->getProbid();
+            $probid = $problem->getExternalid();
             $errors = $this->validator->validate($problem);
             if (count($errors)) {
                 $result = 'E';
@@ -638,20 +638,21 @@ public function checkProblemsValidate(): ConfigCheckItem
                 ->select('tc.testcaseid', 'tc.ranknumber', 'length(tcc.output) as output_size' )
                 ->from(Testcase::class, 'tc')
                 ->join('tc.content', 'tcc')
-                ->andWhere('tc.problem = :probid')
+                ->join('tc.problem', 'p')
+                ->andWhere('p.externalid = :probid')
                 ->setParameter('probid', $probid)
                 ->getQuery()
                 ->getResult();
             if (count($tcs_size) === 0) {
                 $result = 'E';
-                $moreproblemerrors[$probid] .= sprintf("  - No testcases for `p%s`\n", $probid);
+                $moreproblemerrors[$probid] .= sprintf("  - No testcases for `%s`\n", $probid);
             } else {
                 $problem_output_limit = 1024 * ($problem->getOutputLimit() ?: $output_limit);
                 foreach ($tcs_size as $row) {
                     if ($row['output_size'] > $problem_output_limit) {
                         $result = 'E';
                         $moreproblemerrors[$probid] .= sprintf(
-                            "  - Testcase `%s` for `p%s` exceeds output limit of `%s`\n",
+                            "  - Testcase `%s` for `%s` exceeds output limit of `%s`\n",
                             $row['rank'], $probid, $problem_output_limit
                         );
                     }
@@ -662,7 +663,7 @@ public function checkProblemsValidate(): ConfigCheckItem
                 if (!$contestProblem->getAllowJudge()) {
                     $result = 'E';
                     $moreproblemerrors[$probid] .= sprintf(
-                        "  - `p%s` is disabled in contest `%s`\n",
+                        "  - `%s` is disabled in contest `%s`\n",
                         $probid, $contestProblem->getContest()->getName()
                     );
                 }
@@ -671,7 +672,7 @@ public function checkProblemsValidate(): ConfigCheckItem
 
         $desc = '';
         foreach ($problemerrors as $probid => $errors) {
-            $desc .= "  - Problem `p$probid`:\n";
+            $desc .= "  - Problem `$probid`:\n";
             if (count($errors) > 0 || !empty($moreproblemerrors[$probid])) {
                 /* @phpstan-ignore-next-line */
                 $desc .= (string)$errors . " " .
@@ -698,7 +699,7 @@ public function checkLanguagesValidate(): ConfigCheckItem
         $languageerrors = $morelanguageerrors = [];
         $result = 'O';
         foreach ($languages as $language) {
-            $langid = $language->getLangid();
+            $langid = $language->getExternalid();
             $errors = $this->validator->validate($language);
             if (count($errors)) {
                 $result = 'E';
@@ -969,7 +970,7 @@ protected function checkExternalIdentifiers(string $class): ConfigCheckItem
                     $getter              = sprintf('get%s', ucfirst($column));
                     $routeParams[$param] = $entity->{$getter}();
                 }
-                $description .= sprintf("  - [%s %s](%s) does not have an external ID\n",
+                $description .= sprintf("  - [%s %s](%s) does not have an ID\n",
                                         ucfirst(str_replace('_', ' ', $inflector->tableize($entityType))),
                                         htmlspecialchars(implode(', ', $metadata->getIdentifierValues($entity))),
                                         $this->router->generate($route, $routeParams)
diff --git a/webapp/src/Service/DOMJudgeService.php b/webapp/src/Service/DOMJudgeService.php
index ab5a9ce060..9c8f4b961c 100644
--- a/webapp/src/Service/DOMJudgeService.php
+++ b/webapp/src/Service/DOMJudgeService.php
@@ -150,7 +150,7 @@ public function getCurrentContests(
         }
         $now = Utils::now();
         $qb  = $this->em->createQueryBuilder();
-        $qb->select('c')->from(Contest::class, 'c', 'c.cid');
+        $qb->select('c')->from(Contest::class, 'c', 'c.externalid');
         if (isset($onlyOfTeam)) {
             $qb->leftJoin('c.teams', 'ct')
                 ->leftJoin('c.team_categories', 'tc')
@@ -196,7 +196,7 @@ public function getCurrentContest(?int $onlyOfTeam = null, bool $onlyPublic = fa
             }
 
             foreach ($contests as $contest) {
-                if ($contest->getCid() == $selected_cid) {
+                if ($contest->getExternalid() == $selected_cid) {
                     return $contest;
                 }
             }
@@ -311,7 +311,7 @@ public function clearCookie(
     }
 
     /**
-     * @return array<array{'clarid': int, 'body': string}>
+     * @return list<array{clarid: string, body: string}>
      */
     public function getUnreadClarifications(): array
     {
@@ -326,7 +326,7 @@ public function getUnreadClarifications(): array
         foreach ($clarifications as $clar) {
             if ($clar->getContest()->getCid() === $contest->getCid()) {
                 $unreadClarifications[] = [
-                    'clarid' => $clar->getClarid(),
+                    'clarid' => $clar->getExternalid(),
                     'body' => $clar->getBody(),
                 ];
             }
@@ -360,7 +360,7 @@ public function getUpdates(): array
         if ($this->checkRole('jury')) {
             if ($contest) {
                 $clarifications = $this->em->createQueryBuilder()
-                    ->select('clar.clarid', 'clar.body')
+                    ->select('clar.externalid', 'clar.body')
                     ->from(Clarification::class, 'clar')
                     ->andWhere('clar.contest = :contest')
                     ->andWhere('clar.sender is not null')
@@ -504,11 +504,11 @@ public function withAllRoles(callable $callable, ?UserInterface $user = null): v
      */
     public function auditlog(
         string $datatype,
-        mixed $dataid,
+        string|null $dataid,
         string $action,
         mixed $extraInfo = null,
         ?string $forceUsername = null,
-        string|int|null $cid = null
+        string|null $cid = null
     ): void {
         if (!empty($forceUsername)) {
             $user = $forceUsername;
@@ -516,10 +516,6 @@ public function auditlog(
             $user = $this->getUser() ? $this->getUser()->getUsername() : null;
         }
 
-        if (gettype($cid) == 'string') {
-            $cid = (int) $cid;
-        }
-
         $auditLog = new AuditLog();
         $auditLog
             ->setLogtime(Utils::now())
@@ -759,7 +755,7 @@ public function printUserFile(
      *
      * @param string      $filename The on-disk file to be printed out
      * @param string      $origname The original filename as submitted by the team
-     * @param string|null $language Langid of the programming language this file is in
+     * @param string|null $language External ID of the programming language this file is in
      * @param string      $username Username of the print job submitter
      * @param string|null $teamname Teamname of the team this user belongs to, if any
      * @param string|null $teamid   Teamid of the team this user belongs to, if any
@@ -1166,7 +1162,7 @@ public function helperUnblockJudgeTasks(): QueryBuilder
             ->where('jt.jobid IS NULL');
     }
 
-    public function unblockJudgeTasksForLanguage(string $langId): void
+    public function unblockJudgeTasksForLanguage(int $langId): void
     {
         // These are all the judgings that don't have associated judgetasks yet. Check whether we unblocked them.
         $judgings = $this->helperUnblockJudgeTasks()
@@ -1201,7 +1197,7 @@ public function unblockJudgeTasksForSubmission(string $submissionId): void
         // These are all the judgings that don't have associated judgetasks yet. Check whether we unblocked them.
         $judgings = $this->helperUnblockJudgeTasks()
             ->join(Submission::class, 's', Join::WITH, 'j.submission = s.submitid')
-            ->andWhere('j.submission = :submissionid')
+            ->andWhere('s.externalid = :submissionid')
             ->setParameter('submissionid', $submissionId)
             ->getQuery()
             ->getResult();
diff --git a/webapp/src/Service/ImportExportService.php b/webapp/src/Service/ImportExportService.php
index b6e4c21812..89361a26ba 100644
--- a/webapp/src/Service/ImportExportService.php
+++ b/webapp/src/Service/ImportExportService.php
@@ -551,7 +551,7 @@ public function getResultsData(
             ->getResult();
         $categoryIds = [];
         foreach ($categories as $category) {
-            $categoryIds[] = $category->getCategoryid();
+            $categoryIds[] = $category->getExternalid();
         }
 
         $scoreIsInSeconds = (bool)$this->config->get('score_in_seconds');
@@ -894,7 +894,7 @@ protected function importGroupData(
         foreach ($allCategories as $category) {
             $this->em->persist($category);
             $this->em->flush();
-            $this->dj->auditlog('team_category', $category->getCategoryid(), 'replaced',
+            $this->dj->auditlog('team_category', $category->getExternalid(), 'replaced',
                 'imported from tsv / json');
         }
 
@@ -1004,7 +1004,7 @@ protected function importOrganizationData(
         foreach ($allOrganizations as $organization) {
             $this->em->persist($organization);
             $this->em->flush();
-            $this->dj->auditlog('team_affiliation', $organization->getAffilid(), 'replaced',
+            $this->dj->auditlog('team_affiliation', $organization->getExternalid(), 'replaced',
                 'imported from tsv / json');
         }
 
@@ -1370,21 +1370,21 @@ protected function importTeamData(array $teamData, ?string &$message, ?array &$s
             $this->em->persist($affiliation);
             $this->em->flush();
             $this->dj->auditlog('team_affiliation',
-                $affiliation->getAffilid(),
+                $affiliation->getExternalid(),
                 'added', 'imported from tsv / json');
         }
 
         foreach ($createdCategories as $category) {
             $this->em->persist($category);
             $this->em->flush();
-            $this->dj->auditlog('team_category', $category->getCategoryid(),
+            $this->dj->auditlog('team_category', $category->getExternalid(),
                                     'added', 'imported from tsv');
         }
 
         foreach ($allTeams as $team) {
             $this->em->persist($team);
             $this->em->flush();
-            $this->dj->auditlog('team', $team->getTeamid(), 'replaced', 'imported from tsv');
+            $this->dj->auditlog('team', $team->getExternalid(), 'replaced', 'imported from tsv');
         }
 
         if ($contest = $this->dj->getCurrentContest()) {
@@ -1481,7 +1481,7 @@ protected function importAccountData(
                             ->setExternalid((string)$teamId)
                             ->setName($teamId . ' - auto-create during import');
                         $this->em->persist($team);
-                        $this->dj->auditlog('team', $team->getTeamid(),
+                        $this->dj->auditlog('team', $team->getExternalid(),
                             'added', 'imported from tsv');
                     }
                 }
@@ -1532,14 +1532,15 @@ protected function importAccountData(
         $this->em->flush();
 
         foreach ($allUsers as $user) {
-            $this->dj->auditlog('user', $user->getUserid(), 'replaced', 'imported from tsv');
+            $this->dj->auditlog('user', $user->getExternalid(), 'replaced', 'imported from tsv');
         }
 
         if ($contest = $this->dj->getCurrentContest()) {
             foreach ($newTeams as $newTeam) {
+                /** @var Team $team */
                 $team = $newTeam['team'];
                 $action = $newTeam['action'];
-                $this->dj->auditlog('team', $team->getTeamid(), 'replaced',
+                $this->dj->auditlog('team', $team->getExternalid(), 'replaced',
                     'imported from tsv, autocreated for judge');
                 $this->eventLogService->log('team', $team->getTeamid(), $action, $contest->getCid());
             }
diff --git a/webapp/src/Service/ImportProblemService.php b/webapp/src/Service/ImportProblemService.php
index b69a087500..840759d717 100644
--- a/webapp/src/Service/ImportProblemService.php
+++ b/webapp/src/Service/ImportProblemService.php
@@ -684,7 +684,7 @@ public function importZippedProblem(
                     $extension = end($parts);
                     foreach ($allowedLanguages as $language) {
                         if (in_array($extension, $language->getExtensions())) {
-                            $languageToUse = $language->getLangid();
+                            $languageToUse = $language->getExternalid();
                             break 2;
                         }
                     }
@@ -883,7 +883,7 @@ public function importProblemFromRequest(Request $request, ?int $contestId = nul
             );
             $allMessages = array_merge($allMessages, $messages);
             if ($newProblem) {
-                $this->dj->auditlog('problem', $newProblem->getProbid(), 'upload zip', $clientName);
+                $this->dj->auditlog('problem', $newProblem->getExternalid(), 'upload zip', $clientName);
                 $probId = $newProblem->getExternalid();
             } else {
                 $errors = array_merge($errors, $messages);
diff --git a/webapp/src/Service/RejudgingService.php b/webapp/src/Service/RejudgingService.php
index 629dfc3418..5cf79ae67b 100644
--- a/webapp/src/Service/RejudgingService.php
+++ b/webapp/src/Service/RejudgingService.php
@@ -232,7 +232,7 @@ public function finishRejudging(Rejudging $rejudging, string $action, ?callable
             ->getQuery()
             ->getResult();
 
-        $this->dj->auditlog('rejudging', $rejudgingId, $action . 'ing rejudge', '(start)');
+        $this->dj->auditlog('rejudging', (string)$rejudgingId, $action . 'ing rejudge', '(start)');
 
         // Add missing state events for all active contests. We do this here
         // and disable doing it in the loop when calling EventLogService::log,
@@ -400,7 +400,7 @@ public function finishRejudging(Rejudging $rejudging, string $action, ?callable
             ->setValid($action === self::ACTION_APPLY);
         $this->em->flush();
 
-        $this->dj->auditlog('rejudging', $rejudgingId, $action . 'ing rejudge', '(end)');
+        $this->dj->auditlog('rejudging', (string)$rejudgingId, $action . 'ing rejudge', '(end)');
 
         return true;
     }
diff --git a/webapp/src/Service/ScoreboardService.php b/webapp/src/Service/ScoreboardService.php
index db9e99ecd7..89d4a11344 100644
--- a/webapp/src/Service/ScoreboardService.php
+++ b/webapp/src/Service/ScoreboardService.php
@@ -88,11 +88,11 @@ public function getScoreboard(
      * scorecache table.
      *
      * @param Contest $contest         The contest to get the scoreboard for.
-     * @param int     $teamId          The ID of the team to get the scoreboard for.
+     * @param string  $teamId          The ID of the team to get the scoreboard for.
      * @param bool    $showFtsInFreeze If false, the scoreboard will hide first
      *                                 to solve for submissions after contest freeze.
      */
-    public function getTeamScoreboard(Contest $contest, int $teamId, bool $showFtsInFreeze = true): ?Scoreboard
+    public function getTeamScoreboard(Contest $contest, string $teamId, bool $showFtsInFreeze = true): ?Scoreboard
     {
         $freezeData = new FreezeData($contest);
 
@@ -606,7 +606,7 @@ public function refreshCache(Contest $contest, ?callable $progressReporter = nul
     {
         Utils::extendMaxExecutionTime(300);
 
-        $this->dj->auditlog('contest', $contest->getCid(), 'refresh scoreboard cache');
+        $this->dj->auditlog('contest', $contest->getExternalid(), 'refresh scoreboard cache');
 
         if ($progressReporter === null) {
             $progressReporter = static function (int $progress, string $log, ?string $message = null) {
@@ -657,7 +657,7 @@ public function refreshCache(Contest $contest, ?callable $progressReporter = nul
                 $log .= ', ';
             }
             $first = false;
-            $log .= sprintf('t%d', $team->getTeamid());
+            $log .= $team->getExternalid();
             $progress = (int)round($index / count($teams) * 100);
             $progressReporter($progress, $log);
 
@@ -820,7 +820,7 @@ public function getFilterValues(Contest $contest, bool $jury): array
         /** @var TeamCategory[] $categories */
         $categories = $queryBuilder->getQuery()->getResult();
         foreach ($categories as $category) {
-            $filters['categories'][$category->getCategoryid()] = $category->getName();
+            $filters['categories'][$category->getExternalid()] = $category->getName();
         }
 
         // Show only affiliations / countries with visible teams.
@@ -845,7 +845,7 @@ public function getFilterValues(Contest $contest, bool $jury): array
             /** @var TeamAffiliation[] $affiliations */
             $affiliations = $queryBuilder->getQuery()->getResult();
             foreach ($affiliations as $affiliation) {
-                $filters['affiliations'][$affiliation->getAffilid()] = $affiliation->getName();
+                $filters['affiliations'][$affiliation->getExternalid()] = $affiliation->getName();
                 if ($showFlags && $affiliation->getCountry() !== null) {
                     $filters['countries'][] = $affiliation->getCountry();
                 }
@@ -983,13 +983,13 @@ protected function getTeamsInOrder(Contest $contest, bool $jury = false, ?Filter
         if ($filter) {
             if ($filter->affiliations) {
                 $queryBuilder
-                    ->andWhere('t.affiliation IN (:affiliations)')
+                    ->andWhere('ta.externalid IN (:affiliations)')
                     ->setParameter('affiliations', $filter->affiliations);
             }
 
             if ($filter->categories) {
                 $queryBuilder
-                    ->andWhere('t.category IN (:categories)')
+                    ->andWhere('tc.externalid IN (:categories)')
                     ->setParameter('categories', $filter->categories);
             }
 
@@ -1001,7 +1001,7 @@ protected function getTeamsInOrder(Contest $contest, bool $jury = false, ?Filter
 
             if ($filter->teams) {
                 $queryBuilder
-                    ->andWhere('t.teamid IN (:teams)')
+                    ->andWhere('t.externalid IN (:teams)')
                     ->setParameter('teams', $filter->teams);
             }
         }
diff --git a/webapp/src/Service/StatisticsService.php b/webapp/src/Service/StatisticsService.php
index 7dcf9f6181..0612a389b8 100644
--- a/webapp/src/Service/StatisticsService.php
+++ b/webapp/src/Service/StatisticsService.php
@@ -96,12 +96,12 @@ public function getTeams(Contest $contest, string $filter): array
      *               problem_num_testcases: int[], team_num_submissions: int[],
      *               team_attempted_n_problems: int[], teams_solved_n_problems: int[],
      *               problem_attempts: int[], problem_solutions: int[],
-     *               problem_stats: array{teams_attempted: array<int[]>, teams_solved: array<int[]>},
+     *               problem_stats: array{teams_attempted: array<string, array<string, string>>, teams_solved: array<string, array<string, string>>},
      *               submissions: Submission[], misery_index: float,
      *               team_stats: array<array{total_submitted: int, total_accepted: int,
      *                                       problems_submitted: int[], problems_accepted: int[]}>,
      *               language_stats: array{total_submissions: array<string, int>, total_solutions: array<string, int>,
-     *                                     teams_attempted: array<string, int[]>, teams_solved: array<string, int[]>}}
+     *                                     teams_attempted: array<string, array<string, string>>, teams_solved: array<string, array<string, string>>}}
      */
     public function getMiscContestStatistics(
         Contest $contest,
@@ -177,14 +177,14 @@ public function getMiscContestStatistics(
                 $misc['total_submissions']++;
                 $teamStats['total_submitted']++;
                 static::setOrIncrement($misc['problem_attempts'],
-                    $s->getProblem()->getProbId());
+                    $s->getProblem()->getExternalid());
                 static::setOrIncrement($teamStats['problems_submitted'],
-                    $s->getProblem()->getProbId());
-                $misc['problem_stats']['teams_attempted'][$s->getProblem()->getProbId()][$team->getTeamId()] = $team->getTeamId();
+                    $s->getProblem()->getExternalid());
+                $misc['problem_stats']['teams_attempted'][$s->getProblem()->getExternalid()][$team->getExternalid()] = $team->getExternalid();
 
                 static::setOrIncrement($misc['language_stats']['total_submissions'],
                     $s->getLanguage()->getName());
-                $misc['language_stats']['teams_attempted'][$s->getLanguage()->getName()][$team->getTeamId()] = $team->getTeamId();
+                $misc['language_stats']['teams_attempted'][$s->getLanguage()->getName()][$team->getExternalid()] = $team->getExternalid();
 
                 if ($s->getResult() != 'correct') {
                     continue;
@@ -192,12 +192,12 @@ public function getMiscContestStatistics(
                 $misc['total_accepted']++;
                 $teamStats['total_accepted']++;
                 static::setOrIncrement($teamStats['problems_accepted'],
-                    $s->getProblem()->getProbId());
+                    $s->getProblem()->getExternalid());
                 static::setOrIncrement($misc['problem_solutions'],
-                    $s->getProblem()->getProbId());
-                $misc['problem_stats']['teams_solved'][$s->getProblem()->getProbId()][$team->getTeamId()] = $team->getTeamId();
+                    $s->getProblem()->getExternalid());
+                $misc['problem_stats']['teams_solved'][$s->getProblem()->getExternalid()][$team->getExternalid()] = $team->getExternalid();
 
-                $misc['language_stats']['teams_solved'][$s->getLanguage()->getName()][$team->getTeamId()] = $team->getTeamId();
+                $misc['language_stats']['teams_solved'][$s->getLanguage()->getName()][$team->getExternalid()] = $team->getExternalid();
                 static::setOrIncrement($misc['language_stats']['total_solutions'],
                     $s->getLanguage()->getName());
 
@@ -205,7 +205,7 @@ public function getMiscContestStatistics(
                     $lastSubmission = $s;
                 }
             }
-            $misc['team_stats'][$team->getTeamId()] = $teamStats;
+            $misc['team_stats'][$team->getExternalid()] = $teamStats;
             static::setOrIncrement($misc['team_attempted_n_problems'],
                 count($teamStats['problems_submitted']));
             static::setOrIncrement($misc['teams_solved_n_problems'],
@@ -222,7 +222,7 @@ public function getMiscContestStatistics(
             }
             $miseryMinutes = ($miserySeconds / 60) * 3;
 
-            $misc['team_stats'][$team->getTeamId()]['misery_index'] = $miseryMinutes;
+            $misc['team_stats'][$team->getExternalid()]['misery_index'] = $miseryMinutes;
             $totalMiseryMinutes += $miseryMinutes;
         }
         $misc['misery_index'] = count($teams) > 0 ? $totalMiseryMinutes / count($teams) : 0;
@@ -656,7 +656,7 @@ protected function getNumTestcases(Contest $contest): array
         // Need to query directly the count, otherwise symfony memory explodes
         // I think because it tries to load the testdata if you do this the naive way.
         $results = $this->em->createQueryBuilder()
-            ->select('p.probid, count(tc.testcaseid) as num_testcases')
+            ->select('p.externalid, count(tc.testcaseid) as num_testcases')
             ->from(Contest::class, 'c')
             ->join('c.problems', 'cp')
             ->join('cp.problem', 'p')
@@ -667,7 +667,7 @@ protected function getNumTestcases(Contest $contest): array
             ->getQuery()->getResult();
         $numTestcases = [];
         foreach ($results as $r) {
-            $numTestcases[$r['probid']] = $r['num_testcases'];
+            $numTestcases[$r['externalid']] = $r['num_testcases'];
         }
 
         return $numTestcases;
diff --git a/webapp/src/Service/SubmissionService.php b/webapp/src/Service/SubmissionService.php
index 010fd8e59d..5c3622c2c1 100644
--- a/webapp/src/Service/SubmissionService.php
+++ b/webapp/src/Service/SubmissionService.php
@@ -84,11 +84,12 @@ public function getSubmissionList(
 
         $queryBuilder = $this->em->createQueryBuilder()
             ->from(Submission::class, 's')
-            ->select('s', 'j', 'cp')
+            ->select('s', 'j', 'cp', 'l')
             ->join('s.team', 't')
             ->join('s.contest_problem', 'cp')
+            ->join('s.language', 'l')
             ->andWhere('s.contest IN (:contests)')
-            ->setParameter('contests', array_keys($contests))
+            ->setParameter('contests', $contests)
             ->orderBy('s.submittime', 'DESC')
             ->addOrderBy('s.submitid', 'DESC');
 
@@ -470,7 +471,7 @@ public function submitSolution(
             ]);
         }
         if (!$language instanceof Language) {
-            $language = $this->em->getRepository(Language::class)->find($language);
+            $language = $this->em->getRepository(Language::class)->findByExternalId($language);
         }
         if ($originalSubmission !== null && !$originalSubmission instanceof Submission) {
             $originalSubmission = $this->em->getRepository(Submission::class)->find($originalSubmission);
@@ -769,8 +770,8 @@ public function submitSolution(
                                            $submission->getSubmitid(), $team->getTeamid(),
                                            $language->getLangid(), $problem->getProblem()->getProbid()));
 
-        $this->dj->auditlog('submission', $submission->getSubmitid(), 'added',
-            'via ' . $source->value, null, $contest->getCid());
+        $this->dj->auditlog('submission', $submission->getExternalid(), 'added',
+            'via ' . $source->value, null, $contest->getExternalid());
 
         if (Utils::difftime((float)$contest->getEndtime(), $submitTime) <= 0) {
             $this->logger->info(
diff --git a/webapp/src/Twig/TwigExtension.php b/webapp/src/Twig/TwigExtension.php
index 07fd305a48..b609e2159c 100644
--- a/webapp/src/Twig/TwigExtension.php
+++ b/webapp/src/Twig/TwigExtension.php
@@ -935,7 +935,7 @@ public function codeEditor(
      *      source: string,
      *      renamedFrom?: string
      * }> $files */
-    public function showDiff(string $editorId, string $diffId, int $submissionId, string $filename, array $files): string
+    public function showDiff(string $editorId, string $diffId, string $submissionId, string $filename, array $files): string
     {
         $editor = <<<HTML
 <div class="editor" id="$diffId"></div>
@@ -943,7 +943,7 @@ public function showDiff(string $editorId, string $diffId, int $submissionId, st
 $(function() {
     const editorId = '%s';
     const diffId = '%s';
-    const submissionId = %d;
+    const submissionId = '%s';
     const models = %s;
     require(['vs/editor/editor.main'], () => {
         initDiffEditorTab(editorId, diffId, submissionId, models);
@@ -1295,20 +1295,14 @@ public function printWarningContent(ExternalSourceWarning $warning): string
 
     /**
      * Get the entity ID badge to display for the given entity.
-     *
-     * When we are in a data source mode that uses external ID's, those will be used and the
-     * internal ID will be shown in a tooltip.
-     *
-     * @param string $idPrefix The prefix to use for the internal ID, if any.
      */
-    public function entityIdBadge(BaseApiEntity $entity, string $idPrefix = ''): string
+    public function entityIdBadge(BaseApiEntity $entity): string
     {
         $propertyAccessor = PropertyAccess::createPropertyAccessor();
         $metadata = $this->em->getClassMetadata($entity::class);
         $primaryKeyColumn = $metadata->getIdentifierColumnNames()[0];
 
         $data = [
-            'idPrefix' => $idPrefix,
             'id' => $propertyAccessor->getValue($entity, $primaryKeyColumn),
             'externalId' => null,
         ];
diff --git a/webapp/src/Utils/Scoreboard/Filter.php b/webapp/src/Utils/Scoreboard/Filter.php
index 1dee9340b1..0ca2f12332 100644
--- a/webapp/src/Utils/Scoreboard/Filter.php
+++ b/webapp/src/Utils/Scoreboard/Filter.php
@@ -5,10 +5,10 @@
 class Filter
 {
     /**
-     * @param int[] $affiliations
+     * @param string[] $affiliations
      * @param string[] $countries
-     * @param int[] $categories
-     * @param int[] $teams
+     * @param string[] $categories
+     * @param string[] $teams
      */
     public function __construct(
         public array $affiliations = [],
diff --git a/webapp/templates/jury/analysis/contest_overview.html.twig b/webapp/templates/jury/analysis/contest_overview.html.twig
index 8b5f628b3d..b3fcd8df3c 100644
--- a/webapp/templates/jury/analysis/contest_overview.html.twig
+++ b/webapp/templates/jury/analysis/contest_overview.html.twig
@@ -113,7 +113,7 @@ $(function() {
             </thead>
             <tbody>
             {% for p in problems %}
-              {% set id=p.probid %}
+              {% set id=p.externalId %}
               <tr>
                 {% set link = path('analysis_problem', {'probid': id, 'view': view}) %}
                 <td scope="row"><a href="{{ path('analysis_problem', {'probid': id, 'view': view}) }}">{{ id }}</a></td>
@@ -149,10 +149,10 @@ $(function() {
             </thead>
             <tbody>
             {% for t in teams %}
-              {% set id=t.teamid %}
+              {% set id=t.externalid %}
               <tr>
                 {% set link = path('analysis_team', {'team':id}) %}
-                <td scope="row" style="text-align: right;"><a href="{{ link }}">{{ t | entityIdBadge('t') }}</a></td>
+                <td scope="row" style="text-align: right;"><a href="{{ link }}">{{ t | entityIdBadge }}</a></td>
                 <td><a href="{{ link }}">{% if t.affiliation %}{{ t.affiliation.name }}{% else %}-{% endif %}</a></td>
                 <td class="truncate" style="max-width: 200px"><a href="{{ link }}">{{ t.effectiveName }}</a></td>
                 <td><a href="{{ link }}">{{ misc.team_stats[id].total_submitted }} / {{ misc.team_stats[id].total_accepted }}</a></td>
@@ -186,7 +186,7 @@ $(function() {
                           </thead>
                           <tbody>
                           {% for j in delayed_judgings.data %}
-                              {% set id=j.submitid %}
+                              {% set id=j.submitexternalid %}
                               <tr>
                                   {% set link = path('jury_submission', {'submitId': id}) %}
                                   <td scope="row"><a href="{{ link }}">{{ id }}</a></td>
@@ -289,7 +289,7 @@ var problem_stats = [
       {% for prob in problems %}
         {
           "label" : "{{ prob.shortname }}",
-          "value" : {{ misc.problem_stats.teams_attempted[prob.probid] | default([]) | length }},
+          "value" : {{ misc.problem_stats.teams_attempted[prob.externalId] | default([]) | length }},
         },
       {% endfor %}
     ]
@@ -301,7 +301,7 @@ var problem_stats = [
       {% for prob in problems %}
         {
           "label" : "{{ prob.shortname }}",
-          "value" : {{ misc.problem_stats.teams_solved[prob.probid] | default([]) | length }},
+          "value" : {{ misc.problem_stats.teams_solved[prob.externalid] | default([]) | length }},
         },
       {% endfor %}
     ]
diff --git a/webapp/templates/jury/analysis/languages.html.twig b/webapp/templates/jury/analysis/languages.html.twig
index 7cb29236af..c299264038 100644
--- a/webapp/templates/jury/analysis/languages.html.twig
+++ b/webapp/templates/jury/analysis/languages.html.twig
@@ -40,12 +40,12 @@
                                         {% for team in language.teams %}
                                             <tr>
                                                 <td>
-                                                    <a href="{{ path('jury_team', {'teamId': team.team.teamid}) }}">
-                                                        {{ team.team | entityIdBadge('t') }}
+                                                    <a href="{{ path('jury_team', {'teamId': team.team.externalid}) }}">
+                                                        {{ team.team | entityIdBadge }}
                                                     </a>
                                                 </td>
                                                 <td>
-                                                    <a href="{{ path('jury_team', {'teamId': team.team.teamid}) }}">
+                                                    <a href="{{ path('jury_team', {'teamId': team.team.externalid}) }}">
                                                         {{ team.team.effectiveName }}
                                                     </a>
                                                 </td>
diff --git a/webapp/templates/jury/analysis/problem.html.twig b/webapp/templates/jury/analysis/problem.html.twig
index 52288a12e6..97843ccab8 100644
--- a/webapp/templates/jury/analysis/problem.html.twig
+++ b/webapp/templates/jury/analysis/problem.html.twig
@@ -1,6 +1,6 @@
 {% extends "jury/base.html.twig" %}
 
-{% block title %}Analysis - Problem {{ problem.probid }} {{ current_contest.shortname | default('') }} - {{ parent() }}{% endblock %}
+{% block title %}Analysis - Problem {{ problem.externalid }} {{ current_contest.shortname | default('') }} - {{ parent() }}{% endblock %}
 
 {% block extrahead %}
 {{ parent() }}
@@ -20,7 +20,7 @@
 {% endblock %}
 
 {% block content %}
-      <h1>Problem {{ problem.probid }}: <span style="font-size: 60%;">{{ contest_problem | problemBadge }}</span> {{ problem.name }}</h1>
+      <h1>Problem {{ problem.externalid }}: <span style="font-size: 60%;">{{ contest_problem | problemBadge }}</span> {{ problem.name }}</h1>
         {% include 'jury/partials/analysis_filter.html.twig' %}
      </div>
     <div class="col-lg-3 col-sm-6 mt-3">
diff --git a/webapp/templates/jury/analysis/team.html.twig b/webapp/templates/jury/analysis/team.html.twig
index 55b9e97fce..e7a1f569e9 100644
--- a/webapp/templates/jury/analysis/team.html.twig
+++ b/webapp/templates/jury/analysis/team.html.twig
@@ -25,7 +25,7 @@
 {% endblock %}
 
 {% block content %}
-      <h1>Team {{ team.teamid }}: {{ team.effectiveName }}</h1>
+      <h1>Team {{ team.externalid }}: {{ team.effectiveName }}</h1>
     </div>
     <div class="col-lg-3 col-sm-6 mt-3">
       <div class="card">
diff --git a/webapp/templates/jury/balloons.html.twig b/webapp/templates/jury/balloons.html.twig
index 38d87c88fe..32bf0c7a2e 100644
--- a/webapp/templates/jury/balloons.html.twig
+++ b/webapp/templates/jury/balloons.html.twig
@@ -19,7 +19,7 @@
     <h1>Balloons - {{ current_contest.name }}</h1>
 
     {% if isfrozen %}
-        <div class="alert alert-info"><i class="fas fa-snowflake"></i> Scoreboard of c{{ current_contest.cid }} ({{ current_contest.shortname }}) is now frozen.</div>
+        <div class="alert alert-info"><i class="fas fa-snowflake"></i> Scoreboard of {{ current_contest.externalid }} ({{ current_contest.shortname }}) is now frozen.</div>
     {% endif %}
 
     <div class="mb-3">
@@ -37,8 +37,8 @@
                         <select id="affiliation-filter" class="select2 form-control" multiple data-filter-field="affiliation-id"
                                 data-ajax-url="{{ path('jury_ajax_data', {datatype: 'affiliations', select2: true}) }}">
                             {%- for affiliation in filteredAffiliations %}
-                                <option value="{{ affiliation.affilid }}" selected>
-                                    {{ affiliation.name }} (a{{ affiliation.affilid }})
+                                <option value="{{ affiliation.externalid }}" selected>
+                                    {{ affiliation.name }} ({{ affiliation.externalid }})
                                 </option>
                             {%- endfor %}
                         </select>
@@ -54,12 +54,12 @@
                         <label for="category-filter">Filter on category(s)</label>
                         <select id="category-filter" class="select2" multiple data-filter-field="category-id" style="width:100%">
                             {%- for category in filteredCategories %}
-                                <option value="{{ category.categoryid }}" selected>
+                                <option value="{{ category.externalid }}" selected>
                                     {{ category.name }}
                                 </option>
                             {%- endfor %}
                             {%- for category in availableCategories %}
-                                <option value="{{ category.categoryid }}">
+                                <option value="{{ category.externalid }}">
                                     {{ category.name }}
                                 </option>
                             {%- endfor %}
@@ -111,7 +111,7 @@
                     $('select[data-filter-field]').each(function () {
                         var $filterField = $(this);
                         if ($filterField.data('filter-field') == "category-id") {
-                            $filterField.val({{- defaultCategories | json_encode() -}}).trigger('change');
+                            $filterField.val({{- defaultCategories | json_encode() | raw -}}).trigger('change');
                         } else {
                             $filterField.val([]).trigger('change');
                         }
diff --git a/webapp/templates/jury/base.html.twig b/webapp/templates/jury/base.html.twig
index c481bae793..a142c44959 100644
--- a/webapp/templates/jury/base.html.twig
+++ b/webapp/templates/jury/base.html.twig
@@ -27,6 +27,16 @@
         require.config({ paths: { vs: '{{ asset('js/monaco/vs') }}'.replace(/\?.*/, '') } });
         window.editorThemeFolder = '{{ asset('js/monaco/themes') }}'.replace(/\?.*/, '');
     </script>
+    {% if previousNext is defined %}
+        <script>
+            {% if previousNext.previous %}
+            window.previousEntity = '{{ previousNext.previous }}';
+            {% endif %}
+            {% if previousNext.next %}
+            window.nextEntity = '{{ previousNext.next }}';
+            {% endif %}
+        </script>
+    {% endif %}
     <script>
         $(function () {
             /* Show the notification options if the browser supports it */
@@ -75,22 +85,22 @@
         <br/>
 
         <code>s</code> <code>↵</code> open the list of submissions <br/>
-        <code>s</code> <code>[0-9]+</code> <code>↵</code> open a specific submission, e.g. <code>s42↵</code> to go to submission 42 <br/>
+        <code>s</code> <code>[a-zA-Z0-9_.-]+</code> <code>↵</code> open a specific submission, e.g. <code>s42↵</code> to go to submission 42 <br/>
         <br/>
 
         <code>t</code> <code>↵</code> open the list of teams <br/>
-        <code>t</code> <code>[0-9]+</code> <code>↵</code> open to a specific team <br/>
+        <code>t</code> <code>[a-zA-Z0-9_.-]+</code> <code>↵</code> open to a specific team <br/>
         <br/>
 
         <code>p</code> <code>↵</code> open the list of problems <br/>
-        <code>p</code> <code>[0-9]+</code> <code>↵</code> open a specific problem <br/>
+        <code>p</code> <code>[a-zA-Z0-9_.-]+</code> <code>↵</code> open a specific problem <br/>
         <br/>
 
         <code>c</code> <code>↵</code> open the list of clarifications <br/>
-        <code>c</code> <code>[0-9]+</code> <code>↵</code> open a specific clarification <br/>
+        <code>c</code> <code>[a-zA-Z0-9_.-]+</code> <code>↵</code> open a specific clarification <br/>
         <br/>
 
-        <code>Shift + j</code> <code>[0-9]+</code> <code>↵</code> open a specific judging <br/>
+        <code>Shift + j</code> <code>[a-zA-Z0-9_.-]+</code> <code>↵</code> open a specific judging <br/>
         <br/>
 
         <code>Shift + s</code> open the scoreboard<br/>
diff --git a/webapp/templates/jury/check_judgings.html.twig b/webapp/templates/jury/check_judgings.html.twig
index 561005f515..504e00de8a 100644
--- a/webapp/templates/jury/check_judgings.html.twig
+++ b/webapp/templates/jury/check_judgings.html.twig
@@ -40,7 +40,7 @@
                 {% for submitId,result in results %}
                     {% set link = path('jury_submission', {'submitId': submitId}) %}
                     <tr>
-                        <td><a href="{{ link }}">s{{ submitId }}</a></td>
+                        <td><a href="{{ link }}">{{ submitId }}</a></td>
                         <td>
                             <a href="{{ link }}">
                                 {% if result.contestProblem is defined %}
@@ -111,7 +111,7 @@
         After this compare the maximum runtime for <code>Accepted</code>
         solutions and tune those against expected <code>Time Limit Exceeded</code> solutions.<br>
         {% for p in problems %}
-            {% set link = path('analysis_problem', {'probid': p.probid, 'view': 'hidden'}) %}
+            {% set link = path('analysis_problem', {'probid': p.externalId, 'view': 'hidden'}) %}
             <a href="{{ link }}">{{ p | problemBadge }}</a>
         {% endfor %}
     {% endif %}
diff --git a/webapp/templates/jury/clarification.html.twig b/webapp/templates/jury/clarification.html.twig
index e7e7c4d24b..1168028fe1 100644
--- a/webapp/templates/jury/clarification.html.twig
+++ b/webapp/templates/jury/clarification.html.twig
@@ -3,7 +3,7 @@
 {% set origclar = list | first %}
 {% set claimed = not origclar.answered and origclar.from_jurymember is defined %}
 
-{% block title %}Clarification {{ origclar.clarid }} - {{ parent() }}{% endblock %}
+{% block title %}Clarification {{ origclar.externalid }} - {{ parent() }}{% endblock %}
 
 {% block extrahead %}
     {{ parent() }}
@@ -23,10 +23,7 @@
                 <div class="card-header">
                     <div class="row">
                         <div class="col-sm">
-                            Clarification {{ clar.clarid }}
-                            {% if shadowMode() %}
-                                (external ID: {{ clar.externalid }})
-                            {% endif %}
+                            Clarification {{ clar.externalid }}
                         </div>
                         <div class="col-sm text-muted text-end">{{ clar.time | printtimeHover(clar.contest) }}</div>
                     </div>
@@ -37,7 +34,7 @@
                             <div class="col-sm">
                                 From:
                                 {% if clar.from_team is defined %}
-                                    <a href="{{ path('jury_team', {teamId: clar.from_team.teamid}) }}">{{ clar.from_teamname }} {{ clar.from_team | entityIdBadge('t') }}</a>
+                                    <a href="{{ path('jury_team', {teamId: clar.from_team.externalid}) }}">{{ clar.from_teamname }} {{ clar.from_team | entityIdBadge }}</a>
                                 {% else %}
                                     Jury
                                     {% if clar.from_jurymember is defined %}
@@ -58,8 +55,8 @@
                                         <i class="far fa-edit" title="Change subject"></i>
                                     </button>
                                 </span>
-                                <span class="clarification-subject-form" data-current-selected-subject="{{ clar.categoryid }}" data-clarification-id="{{ clar.clarid }}">
-                                    <form action="{{ path('jury_clarification_change_subject', {'clarId': clar.clarid }) }}" method="post" class="d-flex">
+                                <span class="clarification-subject-form" data-current-selected-subject="{{ clar.categoryid }}" data-clarification-id="{{ clar.externalid }}">
+                                    <form action="{{ path('jury_clarification_change_subject', {'clarId': clar.externalid }) }}" method="post" class="d-flex">
                                         <select name="subject" class="subject form-select form-select-sm w-auto" id="subselect">
                                             {% for contest,subject in subjects %}
                                                 <optgroup label="{{ contest }}">
@@ -78,7 +75,7 @@
                         <div class="row">
                             <div class="col-sm">To:
                                 {% if clar.to_team is defined %}
-                                    <a href="{{ path('jury_team', {teamId: clar.to_team.teamid}) }}">{{ clar.to_teamname }} {{ clar.to_team | entityIdBadge('t') }}</a>
+                                    <a href="{{ path('jury_team', {teamId: clar.to_team.externalid}) }}">{{ clar.to_teamname }} {{ clar.to_team | entityIdBadge }}</a>
                                 {% elseif clar.from_team is defined %}
                                     Jury
                                 {% else %}
@@ -92,12 +89,12 @@
                                     {{ clar.queue }}
                                     <button class="btn btn-sm btn-link clarification-queue-change-button"><i class="far fa-edit" title="Change queue"></i></button>
                                 </span>
-                                <span class="clarification-queue-form" data-current-selected-queue="{{ clar.queueid }}" data-clarification-id="{{ clar.clarid }}">
-                                    <form action="{{ path('jury_clarification_change_queue', {'clarId': clar.clarid }) }}" class="d-flex" method="post">
+                                <span class="clarification-queue-form" data-current-selected-queue="{{ clar.queueid }}" data-clarification-id="{{ clar.externalid }}">
+                                    <form action="{{ path('jury_clarification_change_queue', {'clarId': clar.externalid }) }}" class="d-flex" method="post">
                                         <select name="queue" class="queue form-select w-auto form-select-sm" id="qselect">
                                             <option value="unassigned">Unassigned issues</option>
                                             {% for qid,queue in queues %}
-                                                <option value="{{ qid }}"{% if clar.queueid == qid %} selected{% endif %}>{{ queue }}</option>
+                                                <option value="{{ qid }}"{% if clar.queue == qid %} selected{% endif %}>{{ queue }}</option>
                                             {% endfor %}
                                             </select>
                                         <button type="button" class="btn-close clarification-queue-cancel-button ms-2 w-auto" aria-label="Cancel"></button>
@@ -126,7 +123,7 @@
                 </div>
 
                 <div class="col-sm text-center">
-                    <form action="{{ path('jury_clarification_claim', {'clarId': origclar.clarid}) }}" method="post">
+                    <form action="{{ path('jury_clarification_claim', {'clarId': origclar.externalid}) }}" method="post">
                         {% if claimed %}
                             {% if origclar.jurymember_is_me %}
                                 <button class="btn btn-sm btn-outline-success" name="claimed" value="0" type="submit"><i class="fas fa-lock-open"></i> unclaim</button>
@@ -142,7 +139,7 @@
                 </div>
 
                 <div class="col-sm text-end">
-                    <form action="{{ path('jury_clarification_set_answered', {'clarId': origclar.clarid}) }}" method="post">
+                    <form action="{{ path('jury_clarification_set_answered', {'clarId': origclar.externalid}) }}" method="post">
                         {% if origclar.answered %}
                             <button class="btn btn-sm btn-outline-warning" name="answered" value="0" type="submit">
                                 <i class="fas fa-times"></i> set unanswered
diff --git a/webapp/templates/jury/contest.html.twig b/webapp/templates/jury/contest.html.twig
index d18aa5bb5b..b7bd586e70 100644
--- a/webapp/templates/jury/contest.html.twig
+++ b/webapp/templates/jury/contest.html.twig
@@ -1,7 +1,7 @@
 {% extends "jury/base.html.twig" %}
 {% import "jury/jury_macros.twig" as macros %}
 
-{% block title %}Contest {{ contest.cid }} - {{ parent() }}{% endblock %}
+{% block title %}Contest {{ contest.externalid }} - {{ parent() }}{% endblock %}
 
 {% block extrahead %}
     {{ parent() }}
@@ -38,12 +38,7 @@
         <div class="col-lg-5">
             <table class="table table-sm table-striped">
                 <tr>
-                    <th>CID</th>
-                    <td>c{{ contest.cid }}</td>
-                    <td></td>
-                </tr>
-                <tr>
-                    <th>External ID</th>
+                    <th>ID</th>
                     <td>{{ contest.externalid }}</td>
                     <td></td>
                 </tr>
@@ -70,14 +65,14 @@
                             <td>
                                 {% if data.show_button %}
                                     {% set button_label = type ~ " now" %}
-                                    {{ button(path('jury_contest_donow', {'contestId': contest.cid, 'time': type}), button_label, 'primary btn-sm timebutton') }}
+                                    {{ button(path('jury_contest_donow', {'contestId': contest.externalid, 'time': type}), button_label, 'primary btn-sm timebutton') }}
                                 {% endif %}
                                 {% if data.extra_button is defined %}
-                                    {{ button(path('jury_contest_donow', {'contestId': contest.cid, 'time': data.extra_button.type}), data.extra_button.label, 'primary btn-sm timebutton') }}
+                                    {{ button(path('jury_contest_donow', {'contestId': contest.externalid, 'time': data.extra_button.type}), data.extra_button.label, 'primary btn-sm timebutton') }}
                                 {% endif %}
                                 {% if type == 'finalize' %}
                                     {% if contest.finalizetime %}
-                                        {{ button(path('jury_contest_finalize', {'contestId': contest.cid}), 'Update finalization', 'secondary btn-sm timebutton') }}
+                                        {{ button(path('jury_contest_finalize', {'contestId': contest.externalid}), 'Update finalization', 'secondary btn-sm timebutton') }}
                                     {% endif %}
                                 {% endif %}
                             </td>
@@ -97,7 +92,7 @@
                     <tr>
                         <th>Problemset document</th>
                         <td>
-                            <a href="{{ path('jury_contest_problemset', {'cid': contest.cid}) }}">
+                            <a href="{{ path('jury_contest_problemset', {'cid': contest.externalid}) }}">
                                 <i title="view problemset document of the contest"
                                    class="fas fa-file-{{ contest.contestProblemsetType }}"></i>
                             </a>
@@ -148,7 +143,7 @@
                                         <ul>
                                             {% for category in contest.medalCategories %}
                                                 <li>
-                                                    <a href="{{ path('jury_team_category', {'categoryId': category.categoryid}) }}">
+                                                    <a href="{{ path('jury_team_category', {'categoryId': category.externalid}) }}">
                                                         {{ category.name }}
                                                     </a>
                                                 </li>
@@ -182,14 +177,14 @@
                             <em>all teams</em>
                         {% else %}
                             {% for team in contest.teams %}
-                                <a href="{{ path('jury_team', {'teamId': team.teamid}) }}">
-                                    {{ team.effectiveName }} {{ team | entityIdBadge('t') }}
+                                <a href="{{ path('jury_team', {'teamId': team.externalid}) }}">
+                                    {{ team.effectiveName }} {{ team | entityIdBadge }}
                                 </a>
                                 <br>
                             {% endfor %}
                             {% for category in contest.teamCategories %}
                                 All teams from
-                                <a href="{{ path('jury_team_category', {'categoryId': category.categoryid}) }}">
+                                <a href="{{ path('jury_team_category', {'categoryId': category.externalid}) }}">
                                     {{ category.name }}
                                 </a>
                                 <br>
@@ -209,7 +204,7 @@
                         {% endif %}
                         <ul>
                             {% for language in allowedLanguages %}
-                                <li><a href="{{ path('jury_language', {"langId": language.langid}) }}">{{ language.name }}</a></li>
+                                <li><a href="{{ path('jury_language', {"langId": language.externalid}) }}">{{ language.name }}</a></li>
                             {% endfor %}
                         </ul>
                     </td>
@@ -218,7 +213,7 @@
                 <tr>
                     <th>Public static scoreboard ZIP</th>
                     <td>
-                        <a class="btn btn-sm btn-secondary" href="{{ path('jury_scoreboard_data_zip', {contestId: contest.cid, type: 'public'}) }}">
+                        <a class="btn btn-sm btn-secondary" href="{{ path('jury_scoreboard_data_zip', {contestId: contest.externalid, type: 'public'}) }}">
                             <i class="fas fa-download"></i> Download
                         </a>
                     </td>
@@ -227,7 +222,7 @@
                 <tr>
                     <th>Jury (unfrozen) static scoreboard ZIP</th>
                     <td>
-                        <a class="btn btn-sm btn-secondary" href="{{ path('jury_scoreboard_data_zip', {contestId: contest.cid, type: 'unfrozen'}) }}">
+                        <a class="btn btn-sm btn-secondary" href="{{ path('jury_scoreboard_data_zip', {contestId: contest.externalid, type: 'unfrozen'}) }}">
                             <i class="fas fa-download"></i> Download
                         </a>
                     </td>
@@ -236,7 +231,7 @@
                 <tr>
                     <th>Sample data ZIP</th>
                     <td>
-                        <a class="btn btn-sm btn-secondary" href="{{ path('jury_contest_samples_data_zip', {contestId: contest.cid}) }}">
+                        <a class="btn btn-sm btn-secondary" href="{{ path('jury_contest_samples_data_zip', {contestId: contest.externalid}) }}">
                             <i class="fas fa-download"></i> Download
                         </a>
                         <br/>
@@ -321,7 +316,7 @@
                                 <td>{{ removedInterval.starttime | printtimediff(removedInterval.endtime) }}</td>
                                 <td>
                                     <button class="btn btn-sm btn-danger remove-interval-button" type="button"
-                                            data-submit-url="{{ path('jury_contest_remove_interval', {'contestId': contest.cid, 'intervalId': removedInterval.intervalid}) }}">
+                                            data-submit-url="{{ path('jury_contest_remove_interval', {'contestId': contest.externalid, 'intervalId': removedInterval.intervalid}) }}">
                                         <i class="fas fa-trash-alt"></i></button>
                                 </td>
                             </tr>
@@ -398,8 +393,8 @@
                     <tbody>
                     {% for problem in problems %}
                         <tr>
-                            {% set link = path('jury_problem', {'probId': problem.probid}) %}
-                            <td><a href="{{ link }}">p{{ problem.probid }}</a></td>
+                            {% set link = path('jury_problem', {'probId': problem.externalId}) %}
+                            <td><a href="{{ link }}">{{ problem.externalId }}</a></td>
                             <td><a href="{{ link }}">{{ problem.problem.name }}</a></td>
                             <td><a href="{{ link }}">{{ problem.shortname }}</a></td>
                             <td><a href="{{ link }}">{{ problem.points }}</a></td>
@@ -425,14 +420,14 @@
                             </td>
                             <td>
                                 {% if problem.problem.problemstatementType %}
-                                    <a title="view problem statement" href="{{ path('jury_problem_statement', {'probId': problem.probid}) }}">
+                                    <a title="view problem statement" href="{{ path('jury_problem_statement', {'probId': problem.externalId}) }}">
                                         <i class="fas fa-file-{{ problem.problem.problemstatementType }}"></i>
                                     </a>
                                 {% endif %}
                             </td>
                             <td>
                                 {% if is_granted('ROLE_ADMIN') and not contest.isLocked %}
-                                    <a title="Unlink problem from contest" href="{{ path('jury_contest_problem_delete', {'contestId': contest.cid, 'probId': problem.probid}) }}"
+                                    <a title="Unlink problem from contest" href="{{ path('jury_contest_problem_delete', {'contestId': contest.externalid, 'probId': problem.externalId}) }}"
                                        data-ajax-modal>
                                         <i class="fas fa-trash-alt"></i>
                                     </a>
@@ -440,7 +435,7 @@
                             </td>
                             <td>
                                 {% if is_granted('ROLE_ADMIN') %}
-                                    <a title="Judge remaining testcases" href="{{ path('jury_contest_problem_request_remaining', {'contestId': contest.cid, 'probId': problem.probid}) }}">
+                                    <a title="Judge remaining testcases" href="{{ path('jury_contest_problem_request_remaining', {'contestId': contest.externalid, 'probId': problem.externalId}) }}">
                                         <i class="fas fa-gavel"></i>
                                     </a>
                                 {% endif %}
@@ -456,16 +451,16 @@
     <div class="button-row">
         {%- if is_granted('ROLE_ADMIN') -%}
             {% if contest.isLocked %}
-                {{ button(path('jury_contest_unlock', {'contestId': contest.cid}), 'Unlock', 'danger', 'unlock') }}
+                {{ button(path('jury_contest_unlock', {'contestId': contest.externalid}), 'Unlock', 'danger', 'unlock') }}
             {% else %}
-                {{ button(path('jury_contest_edit', {'contestId': contest.cid}), 'Edit', 'primary', 'edit') }}
-                {{ button(path('jury_contest_delete', {'contestId': contest.cid}), 'Delete', 'danger', 'trash-alt', true) }}
-                {{ button(path('jury_contest_lock', {'contestId': contest.cid}), 'Lock', 'secondary', 'lock') }}
+                {{ button(path('jury_contest_edit', {'contestId': contest.externalid}), 'Edit', 'primary', 'edit') }}
+                {{ button(path('jury_contest_delete', {'contestId': contest.externalid}), 'Delete', 'danger', 'trash-alt', true) }}
+                {{ button(path('jury_contest_lock', {'contestId': contest.externalid}), 'Lock', 'secondary', 'lock') }}
             {% endif %}
-            {{ button(path('jury_contest_request_remaining', {'contestId': contest.cid}), 'Judge remaining testcases', 'secondary', 'gavel') }}
+            {{ button(path('jury_contest_request_remaining', {'contestId': contest.externalid}), 'Judge remaining testcases', 'secondary', 'gavel') }}
         {% endif %}
-        {{ button(path('jury_contest_prefetch', {'contestId': contest.cid}), 'Heat up judgehosts with contest data', 'secondary', 'download') }}
-        {% include 'jury/partials/rejudge_form.html.twig' with {table: 'contest', id: contest.cid, buttonClass: 'btn-secondary'} %}
+        {{ button(path('jury_contest_prefetch', {'contestId': contest.externalid}), 'Heat up judgehosts with contest data', 'secondary', 'download') }}
+        {% include 'jury/partials/rejudge_form.html.twig' with {table: 'contest', id: contest.externalid, buttonClass: 'btn-secondary'} %}
     </div>
 
 {% endblock %}
diff --git a/webapp/templates/jury/contest_edit.html.twig b/webapp/templates/jury/contest_edit.html.twig
index 3391454125..b78d71ec4e 100644
--- a/webapp/templates/jury/contest_edit.html.twig
+++ b/webapp/templates/jury/contest_edit.html.twig
@@ -1,7 +1,7 @@
 {% extends "jury/base.html.twig" %}
 {% import "jury/jury_macros.twig" as macros %}
 
-{% block title %}Edit contest {{ contest.cid }} - {{ parent() }}{% endblock %}
+{% block title %}Edit contest {{ contest.externalid }} - {{ parent() }}{% endblock %}
 
 {% block extrahead %}
     {{ parent() }}
diff --git a/webapp/templates/jury/contest_finalize.html.twig b/webapp/templates/jury/contest_finalize.html.twig
index 3f185353f8..684f6c85d3 100644
--- a/webapp/templates/jury/contest_finalize.html.twig
+++ b/webapp/templates/jury/contest_finalize.html.twig
@@ -26,7 +26,7 @@
             <table class="table table-sm table-striped">
                 <tr>
                     <th>Contest ID</th>
-                    <td>c{{ contest.cid }}</td>
+                    <td>c{{ contest.externalid }}</td>
                 </tr>
                 <tr>
                     <th>Contest name</th>
@@ -47,7 +47,7 @@
         {{ form_row(form.b) }}
         {{ form_row(form.finalizecomment) }}
         {{ form_widget(form.finalize) }}
-        {{ button(path('jury_contest', {'contestId': contest.cid}), 'Cancel', 'secondary') }}
+        {{ button(path('jury_contest', {'contestId': contest.externalid}), 'Cancel', 'secondary') }}
         {{ form_end(form) }}
     {% endif %}
 
diff --git a/webapp/templates/jury/contests.html.twig b/webapp/templates/jury/contests.html.twig
index 78db62934b..57aeddcfdf 100644
--- a/webapp/templates/jury/contests.html.twig
+++ b/webapp/templates/jury/contests.html.twig
@@ -19,11 +19,11 @@
             <div class="col-lg-8">
                 <div class="card">
                     <div class="card-header">
-                        {{ contest.name }} ({{ contest.shortname }} - c{{ contest.cid }})
+                        {{ contest.name }} ({{ contest.shortname }} - {{ contest.externalid }})
                         {% if contest.locked %}
                             <i class="fas fa-lock"></i>
                         {% endif %}
-                        <a class="fa-regular fa-folder-open" style="float: right; color: black" href={{ path('jury_contest', {'contestId': contest.cid}) }}></a>
+                        <a class="fa-regular fa-folder-open" style="float: right; color: black" href={{ path('jury_contest', {'contestId': contest.externalid}) }}></a>
                     </div>
                     <div class="card-body">
                         {% if not contest.starttimeEnabled and contest.finalizetime is not empty %}
@@ -46,10 +46,10 @@
                                         <td>
                                             {% if data.show_button %}
                                                 {% set button_label =  type ~ " now" %}
-                                                {{ button(path('jury_contest_donow', {'contestId': contest.cid, 'time': type}), button_label, 'primary btn-sm') }}
+                                                {{ button(path('jury_contest_donow', {'contestId': contest.externalid, 'time': type}), button_label, 'primary btn-sm') }}
                                             {% endif %}
                                             {% if data.extra_button is defined %}
-                                                {{ button(path('jury_contest_donow', {'contestId': contest.cid, 'time': data.extra_button.type}), data.extra_button.label, 'primary btn-sm') }}
+                                                {{ button(path('jury_contest_donow', {'contestId': contest.externalid, 'time': data.extra_button.type}), data.extra_button.label, 'primary btn-sm') }}
                                             {% endif %}
                                         </td>
                                     {% endif %}
@@ -73,7 +73,7 @@
                     <i>{{ upcoming_contest.name }} ({{ upcoming_contest.shortname }})</i>;
                     active from {{ upcoming_contest.activatetime | printtime('D d M Y H:i:s T') }}
                 </p>
-                {{ button(path('jury_contest_donow', {'contestId': upcoming_contest.cid, 'time': 'activate'}), 'Activate now', 'primary') }}
+                {{ button(path('jury_contest_donow', {'contestId': upcoming_contest.externalid, 'time': 'activate'}), 'Activate now', 'primary') }}
             </div>
         {% endif %}
     {% endfor %}
diff --git a/webapp/templates/jury/entity_id_badge.html.twig b/webapp/templates/jury/entity_id_badge.html.twig
index 8e304dc748..df4d37a1f7 100644
--- a/webapp/templates/jury/entity_id_badge.html.twig
+++ b/webapp/templates/jury/entity_id_badge.html.twig
@@ -1,9 +1,9 @@
-<span class="badge text-bg-secondary id-badge" data-bs-toggle="tooltip" data-bs-placement="top" title="{% if label is defined and label | length %}Label: {{ label }}, {% endif %}{% if externalId is not null %}External ID: {{ externalId }}, {% endif %}Internal ID: {{ idPrefix }}{{ id }}">
+<span class="badge text-bg-secondary id-badge" data-bs-toggle="tooltip" data-bs-placement="top" title="{% if label is defined and label | length %}Label: {{ label }}, {% endif %}{% if externalId is not null %}ID: {{ externalId }}{% else %}ID: {{ id }}{% endif %}">
     {% if label is defined and label | length %}
         {{ label }}
     {% elseif externalId is not null %}
         {{ externalId }}
     {% else %}
-        {{ idPrefix }}{{ id }}
+        {{ id }}
     {% endif %}
 </span>
diff --git a/webapp/templates/jury/executable.html.twig b/webapp/templates/jury/executable.html.twig
index 75e85d9a9e..4fee495d7f 100644
--- a/webapp/templates/jury/executable.html.twig
+++ b/webapp/templates/jury/executable.html.twig
@@ -48,21 +48,21 @@
                         {% endif %}
                         {% if executable.type == 'compare' %}
                             {% for problem in executable.problemsCompare %}
-                                <a href="{{ path('jury_problem', {'probId': problem.probid}) }}">
-                                    p{{ problem.probid }} {{ problem | problemBadgeForContest }}
+                                <a href="{{ path('jury_problem', {'probId': problem.externalid}) }}">
+                                    {{ problem.externalid }} {{ problem | problemBadgeForContest }}
                                 </a>
                                 {% set used = true %}
                             {% endfor %}
                         {% elseif executable.type == 'run' %}
                             {% for problem in executable.problemsRun %}
-                                <a href="{{ path('jury_problem', {'probId': problem.probid}) }}">
-                                    p{{ problem.probid }} {{ problem | problemBadgeForContest }}
+                                <a href="{{ path('jury_problem', {'probId': problem.externalid}) }}">
+                                    {{ problem.externalid }} {{ problem | problemBadgeForContest }}
                                 </a>
                                 {% set used = true %}
                             {% endfor %}
                         {% elseif executable.type == 'compile' %}
                             {% for language in executable.languages %}
-                                <a href="{{ path('jury_language', {'langId': language.langid}) }}">
+                                <a href="{{ path('jury_language', {'langId': language.externalid}) }}">
                                     {{ language | entityIdBadge }}
                                 </a>
                                 {% set used = true %}
diff --git a/webapp/templates/jury/export/clarifications.html.twig b/webapp/templates/jury/export/clarifications.html.twig
index 871033868e..ece8c2ad18 100644
--- a/webapp/templates/jury/export/clarifications.html.twig
+++ b/webapp/templates/jury/export/clarifications.html.twig
@@ -64,18 +64,18 @@
             <tbody>
             {% for clarification in clarifications %}
                 <tr class="top-line">
-                    <td>{{ clarification.clarId }}</td>
+                    <td>{{ clarification.externalid }}</td>
                     <td>{{ clarification.submitTime | printtime(null, contest) }}</td>
                     <td>
                         {% if clarification.sender %}
-                            {{ clarification.sender.effectiveName }} {{ clarification.sender | entityIdBadge('t') }}
+                            {{ clarification.sender.effectiveName }} {{ clarification.sender | entityIdBadge }}
                         {% else %}
                             Jury ({{ clarification.juryMember }})
                         {% endif %}
                     </td>
                     <td>
                         {% if clarification.recipient and clarification.sender is empty %}
-                            {{ clarification.recipient.effectiveName }} {{ clarification.recipient | entityIdBadge('t') }}
+                            {{ clarification.recipient.effectiveName }} {{ clarification.recipient | entityIdBadge }}
                         {% elseif clarification.sender %}
                             Jury
                         {% else %}
diff --git a/webapp/templates/jury/internal_error.html.twig b/webapp/templates/jury/internal_error.html.twig
index 4565c5c751..82bcce10c7 100644
--- a/webapp/templates/jury/internal_error.html.twig
+++ b/webapp/templates/jury/internal_error.html.twig
@@ -92,8 +92,8 @@
                     <tr>
                         <th>Related contest</th>
                         <td>
-                            <a href="{{ path('jury_contest', {'contestId': internalError.contest.cid}) }}">
-                                c{{ internalError.contest.cid }}
+                            <a href="{{ path('jury_contest', {'contestId': internalError.contest.externalid}) }}">
+                                {{ internalError.contest.externalid }}
                             </a>
                         </td>
                     </tr>
diff --git a/webapp/templates/jury/jury_macros.twig b/webapp/templates/jury/jury_macros.twig
index 9df0ba8c2e..4c3af41c5e 100644
--- a/webapp/templates/jury/jury_macros.twig
+++ b/webapp/templates/jury/jury_macros.twig
@@ -147,7 +147,7 @@
                                     {{- badge|problemBadge }}
                                 {% endfor %}
                             {% elseif (column.render | default('')) == "entity_id_badge" %}
-                            {% if item.value %}{{- item.value|entityIdBadge(item.idPrefix|default('')) -}}{% endif %}
+                            {% if item.value %}{{- item.value|entityIdBadge -}}{% endif %}
                             {% else %}
                             {%- if column.raw|default(false) %}{{- (item.value|default(item.default|default('')))|raw -}}{% else %}{{- (item.value|default(item.default|default(''))) -}}{% endif -%}
                             {% endif %}
diff --git a/webapp/templates/jury/language.html.twig b/webapp/templates/jury/language.html.twig
index 974a996a4e..e3cc81e4e2 100644
--- a/webapp/templates/jury/language.html.twig
+++ b/webapp/templates/jury/language.html.twig
@@ -1,7 +1,7 @@
 {% extends "jury/base.html.twig" %}
 {% import "jury/jury_macros.twig" as macros %}
 
-{% block title %}Language {{ language.langid }} - {{ parent() }}{% endblock %}
+{% block title %}Language {{ language.externalid }} - {{ parent() }}{% endblock %}
 
 {% block extrahead %}
     {{ parent() }}
@@ -19,10 +19,6 @@
             <table class="table table-sm table-striped">
                 <tr>
                     <th>ID</th>
-                    <td>{{ language.langid }}</td>
-                </tr>
-                <tr>
-                    <th>External ID</th>
                     <td>{{ language.externalid }}</td>
                 </tr>
                 <tr>
@@ -106,11 +102,11 @@
 
     <div class="button-row">
         {%- if is_granted('ROLE_ADMIN') -%}
-            {{ button(path('jury_language_edit', {'langId': language.langid}), 'Edit', 'primary', 'edit') }}
-            {{ button(path('jury_language_delete', {'langId': language.langid}), 'Delete', 'danger', 'trash-alt', true) }}
-            {{ button(path('jury_language_request_remaining', {'langId': language.langid}), 'Judge remaining testcases', 'secondary', 'gavel') }}
+            {{ button(path('jury_language_edit', {'langId': language.externalid}), 'Edit', 'primary', 'edit') }}
+            {{ button(path('jury_language_delete', {'langId': language.externalid}), 'Delete', 'danger', 'trash-alt', true) }}
+            {{ button(path('jury_language_request_remaining', {'langId': language.externalid}), 'Judge remaining testcases', 'secondary', 'gavel') }}
         {% endif %}
-        {% include 'jury/partials/rejudge_form.html.twig' with {table: 'language', id: language.langid, buttonClass: 'btn-secondary'} %}
+        {% include 'jury/partials/rejudge_form.html.twig' with {table: 'language', id: language.externalid, buttonClass: 'btn-secondary'} %}
     </div>
 
     <h3>Recent submissions</h3>
diff --git a/webapp/templates/jury/language_edit.html.twig b/webapp/templates/jury/language_edit.html.twig
index 78afbf22fe..8c8a085e52 100644
--- a/webapp/templates/jury/language_edit.html.twig
+++ b/webapp/templates/jury/language_edit.html.twig
@@ -10,18 +10,7 @@
 
 {% block content %}
 
-    <h1>Edit language {{ language.langid }}</h1>
-
-    <div class="row">
-        <div class="col-lg-4">
-            <table class="table table-sm table-striped">
-                <tr>
-                    <th>Language ID</th>
-                    <td>{{ language.langid }}</td>
-                </tr>
-            </table>
-        </div>
-    </div>
+    <h1>Edit language {{ language.externalid }}</h1>
 
     {% include 'jury/partials/language_form.html.twig' %}
 
diff --git a/webapp/templates/jury/partials/balloon_list.html.twig b/webapp/templates/jury/partials/balloon_list.html.twig
index 4195b59bb6..462dc796ca 100644
--- a/webapp/templates/jury/partials/balloon_list.html.twig
+++ b/webapp/templates/jury/partials/balloon_list.html.twig
@@ -35,7 +35,7 @@
                 <td data-order="{{ balloon.data.time }}">{{ balloon.data.time | printtime }}</td>
                 <td>{{ balloon.data.contestproblem | problemBadge }}</td>
                 <td>
-                    {{ balloon.data.team | entityIdBadge('t') }}
+                    {{ balloon.data.team | entityIdBadge }}
                     {{ balloon.data.team.effectiveName | u.truncate(teamname_max_length, '…') }}
                 </td>
                 <td>{{ balloon.data.affiliation }}</td>
diff --git a/webapp/templates/jury/partials/clarification_list.html.twig b/webapp/templates/jury/partials/clarification_list.html.twig
index 33ffcbcf3e..4c85ee403b 100644
--- a/webapp/templates/jury/partials/clarification_list.html.twig
+++ b/webapp/templates/jury/partials/clarification_list.html.twig
@@ -24,13 +24,10 @@
     </thead>
     <tbody>
     {%- for clarification in clarifications %}
-        {%- set link = path('jury_clarification', {id: clarification.clarid}) %}
+        {%- set link = path('jury_clarification', {id: clarification.externalid}) %}
 
         <tr>
-            <td><a href="{{ link }}">{{ clarification.clarid }}</a></td>
-            {% if shadowMode() %}
-                <td><a href="{{ link }}">{{ clarification.externalid }}</a></td>
-            {% endif %}
+            <td><a href="{{ link }}">{{ clarification.externalid }}</a></td>
             {%- if current_contest is null and current_contests | length > 1 %}
                 <td><a href="{{ link }}">{{ clarification.contest.shortname }}</a></td>
             {%- endif %}
@@ -42,7 +39,7 @@
                     {%- set recipient = 'All' %}
                 {%- else %}
                     {%- set recipient = clarification.recipient.effectiveName %}
-                    {%- set recipientBadge = clarification.recipient | entityIdBadge('t') %}
+                    {%- set recipientBadge = clarification.recipient | entityIdBadge %}
                 {%- endif %}
                 <td style="text-align: right;">
                     <a href="{{ link }}" title="{{ recipient }}">
@@ -56,7 +53,7 @@
                 </td>
             {%- else %}
                 {%- set sender = clarification.sender.effectiveName %}
-                {%- set senderBadge = clarification.sender | entityIdBadge('t') %}
+                {%- set senderBadge = clarification.sender | entityIdBadge %}
                 <td style="text-align: right;">
                     <a href="{{ link }}" title="{{ sender }}">
                         {{ senderBadge | raw }}
@@ -93,7 +90,7 @@
             {%- endif %}
 
             <td><a href="{{ link }}">{{ answered | raw }}</a></td>
-            <td><form action="{{ path('jury_clarification_claim', {clarId: clarification.clarid}) }}" method="post">
+            <td><form action="{{ path('jury_clarification_claim', {clarId: clarification.externalid}) }}" method="post">
                 {%- if claim and clarification.sender -%}
                     <button name="claimed" value="1"
                        class="btn btn-outline-success btn-sm">Claim</button>
@@ -108,12 +105,12 @@
 {% if queues | length > 1 %}
             <td data-search="{{ queues[clarification.queue]|default('') }}">
             <div class="btn-group" role="group">
-                 <span class="input-group-text" id="qig{{clarification.clarid}}"><i class="fab fa-quora"></i></span>
+                 <span class="input-group-text" id="qig{{clarification.externalid}}"><i class="fab fa-quora"></i></span>
                  {% for qk,qv in queues %}
                  <input class="qbut btn-check" type="radio" autocomplete="off"
-                     name="queue[{{ clarification.clarid }}]" data-clarid="{{ clarification.clarid }}" id="q_{{ clarification.clarid }}{{ qk }}" value="{{ qk }}"
+                     name="queue[{{ clarification.externalid }}]" data-clarid="{{ clarification.externalid }}" id="q_{{ clarification.externalid }}{{ qk }}" value="{{ qk }}"
                      {% if qk == clarification.queue %} checked{% endif %}>
-                 <label class="btn btn-sm btn-outline-secondary" for="q_{{ clarification.clarid }}{{ qk }}">{{ qv }}</label>
+                 <label class="btn btn-sm btn-outline-secondary" for="q_{{ clarification.externalid }}{{ qk }}">{{ qv }}</label>
                  {% endfor %}
             </div>
             </td>
diff --git a/webapp/templates/jury/partials/contest_toggle.html.twig b/webapp/templates/jury/partials/contest_toggle.html.twig
index 8d23d4b9ea..607890d296 100644
--- a/webapp/templates/jury/partials/contest_toggle.html.twig
+++ b/webapp/templates/jury/partials/contest_toggle.html.twig
@@ -1,4 +1,4 @@
-<form action="{{ path('jury_contest_toggle', {'contestId': contest.cid, 'type': type}) }}" method="post" class="d-inline">
+<form action="{{ path('jury_contest_toggle', {'contestId': contest.externalid, 'type': type}) }}" method="post" class="d-inline">
     <input type="checkbox" data-toggle="toggle" data-size="mini" data-on="Yes" data-off="No"
            name="value" {% if enabled %}checked{% endif %}>
 </form>
diff --git a/webapp/templates/jury/partials/language_toggle.html.twig b/webapp/templates/jury/partials/language_toggle.html.twig
index 1335bd45d2..1f968e474d 100644
--- a/webapp/templates/jury/partials/language_toggle.html.twig
+++ b/webapp/templates/jury/partials/language_toggle.html.twig
@@ -1,4 +1,4 @@
-<form action="{{ path(path, {'langId': language.langid}) }}" method="post" class="d-inline">
+<form action="{{ path(path, {'langId': language.externalid}) }}" method="post" class="d-inline">
     <input type="checkbox" data-toggle="toggle" data-size="mini" data-on="Yes" data-off="No"
            name="value" {% if value %}checked{% endif %}>
 </form>
diff --git a/webapp/templates/jury/partials/problem_toggle.html.twig b/webapp/templates/jury/partials/problem_toggle.html.twig
index 448061b3f7..1b741e6899 100644
--- a/webapp/templates/jury/partials/problem_toggle.html.twig
+++ b/webapp/templates/jury/partials/problem_toggle.html.twig
@@ -1,4 +1,4 @@
-<form action="{{ path('jury_problem_toggle', {contestId: contestProblem.cid, probId: contestProblem.probId, 'type': type}) }}" method="post" class="d-inline">
+<form action="{{ path('jury_problem_toggle', {contestId: contestProblem.contest.externalid, probId: contestProblem.problem.externalid, 'type': type}) }}" method="post" class="d-inline">
     <input type="checkbox" data-toggle="toggle" data-size="mini" data-on="Yes" data-off="No"
            name="value" {% if enabled %}checked{% endif %}>
 </form>
diff --git a/webapp/templates/jury/partials/submission_diff.html.twig b/webapp/templates/jury/partials/submission_diff.html.twig
index de391147c4..11a64bc550 100644
--- a/webapp/templates/jury/partials/submission_diff.html.twig
+++ b/webapp/templates/jury/partials/submission_diff.html.twig
@@ -4,8 +4,8 @@
     <ul class="nav nav-tabs source-tab-nav align-items-end">
         {%- for name, name_files in files %}
             {% set diff_id = "diff-" ~ name %}
-            {% if name_files[submission.submitid] is defined %}        
-                {% set rank = name_files[submission.submitid].rank %}
+            {% if name_files[submission.externalid] is defined %}
+                {% set rank = name_files[submission.externalid].rank %}
             {% else %}
                 {% set rank = null %}
             {% endif %}
@@ -16,11 +16,11 @@
         {%- endfor %}
 
         <li class="nav-item flex-grow-1 text-end mb-1">
-            <a class="download btn btn-secondary btn-sm" href="{{ path('jury_submission_source', {submission: submission.submitid, fetch: 0}) }}">
+            <a class="download btn btn-secondary btn-sm" href="{{ path('jury_submission_source', {submission: submission.externalid, fetch: 0}) }}">
                 <i class="fas fa-download"></i> Download
             </a>
             {% if allowEdit %}
-                <a class="edit btn btn-secondary btn-sm" href="{{ path('jury_submission_edit_source', {submission: submission.submitid, rank: 0}) }}">
+                <a class="edit btn btn-secondary btn-sm" href="{{ path('jury_submission_edit_source', {submission: submission.externalid, rank: 0}) }}">
                     <i class="fas fa-pencil-alt"></i> Edit
                 </a>
             {% endif %}
@@ -30,7 +30,7 @@
                     <option value="" data-tag="no-diff">No diff</option>
                     {%- for other in otherSubmissions %}
                         <option value="{{ other.submitid }}" data-url="{{ path('jury_submission', {submitId: other.submitid}) }}" {%- if other.tag %} data-tag="{{ other.tag }}" {%- endif %}>
-                            s{{ other.submitid }} {%- if other.tag %} ({{ other.tag }}) {%- endif %}
+                            {{ other.submitid }} {%- if other.tag %} ({{ other.tag }}) {%- endif %}
                         </option>
                     {%- endfor %}
                 </select>
@@ -45,18 +45,18 @@
         </li>
     </ul>
     <script>
-    $(() => {
-        require(['vs/editor/editor.main'], () => {
-            initDiffEditor('{{ editor_id }}');
+        $(() => {
+            require(['vs/editor/editor.main'], () => {
+                initDiffEditor('{{ editor_id }}');
+            });
         });
-    });
     </script>
     {% set extra_css_classes = "show active" %}
     <div class="tab-content source-tab">
         {%- for name, name_files in files %}
             {% set diff_id = "diff-" ~ name %}
             <div class="tab-pane fade {{ extra_css_classes }}" id="{{ diff_id }}-tab" role="tabpanel">
-                {{ showDiff(editor_id, diff_id, submission.submitid, name, name_files) }}
+                {{ showDiff(editor_id, diff_id, submission.externalid, name, name_files) }}
             </div>
             {% set extra_css_classes = "" %}
         {%- endfor %}
diff --git a/webapp/templates/jury/partials/submission_list.html.twig b/webapp/templates/jury/partials/submission_list.html.twig
index 4493e5867d..a67d7f750a 100644
--- a/webapp/templates/jury/partials/submission_list.html.twig
+++ b/webapp/templates/jury/partials/submission_list.html.twig
@@ -88,13 +88,13 @@
         <tbody>
         {%- for submission in submissions %}
             {%- if rejudging is defined %}
-                {%- set link = path('jury_submission', {submitId: submission.submitid, rejudgingid: rejudging.rejudgingid}) %}
+                {%- set link = path('jury_submission', {submitId: submission.externalid, rejudgingid: rejudging.rejudgingid}) %}
             {%- else %}
-                {%- set link = path('jury_submission', {submitId: submission.submitid}) %}
+                {%- set link = path('jury_submission', {submitId: submission.externalid}) %}
             {%- endif %}
 
             {% if submission.team.affiliation %}
-                {% set affilid = submission.team.affiliation.affilid %}
+                {% set affilid = submission.team.affiliation.externalid %}
             {% else %}
                 {% set affilid = '' %}
             {% endif %}
@@ -109,14 +109,11 @@
                 {% endif %}
                 <td class="{{ tdExtraClass }}">
                     <a href="{{ link }}">
-                        s{{ submission.submitid }}
-                        {% if shadowMode() and submission.externalid %}
-                            ({{ submission.externalid }})
-                        {% endif %}
+                        {{ submission.externalid }}
                     </a>
                 </td>
                 {%- if showContest %}
-                    <td class="{{ tdExtraClass }}"><a href="{{ link }}">c{{ submission.contest.cid }}</a></td>
+                    <td class="{{ tdExtraClass }}"><a href="{{ link }}">{{ submission.contest.externalid }}</a></td>
                 {%- endif %}
 
                 <td rowspan="{{ rowSpan }}" class="{{ tdExtraClass }}">
@@ -124,7 +121,7 @@
                 </td>
                 <td rowspan="{{ rowSpan }}" class="{{ tdExtraClass }}" style="text-align: right;">
                     <a href="{{ link }}">
-                        {{ submission.team | entityIdBadge('t') }}
+                        {{ submission.team | entityIdBadge }}
                     </a>
                 </td>
                 <td rowspan="{{ rowSpan }}" class="{{ tdExtraClass }}">
@@ -148,7 +145,7 @@
                     </td>
                 {% endif %}
                 {%- if rejudging is defined %}
-                    <td class="{{ tdExtraClass }}"><a href="{{ path('jury_submission', {submitId: submission.submitid}) }}">
+                    <td class="{{ tdExtraClass }}"><a href="{{ path('jury_submission', {submitId: submission.externalid}) }}">
                             {{ submission.oldResult | printValidJuryResult }}
                         </a></td>
                 {%- endif %}
@@ -205,9 +202,9 @@
                     {% if not showExternalResult or not showExternalTestcases %}
                         <td class="{{ tdExtraClass }}">
                             {%- if rejudging is defined %}
-                                {%- set claimLink = path('jury_submission', claimArg | merge({submitId: submission.submitid, rejudgingid: rejudging.rejudgingid})) %}
+                                {%- set claimLink = path('jury_submission', claimArg | merge({submitId: submission.externalid, rejudgingid: rejudging.rejudgingid})) %}
                             {%- else %}
-                                {%- set claimLink = path('jury_submission', claimArg | merge({submitId: submission.submitid})) %}
+                                {%- set claimLink = path('jury_submission', claimArg | merge({submitId: submission.externalid})) %}
                             {%- endif %}
                             {%- if claim -%}
                                 <a class="btn btn-outline-secondary btn-sm"
diff --git a/webapp/templates/jury/partials/team_score_and_submissions.html.twig b/webapp/templates/jury/partials/team_score_and_submissions.html.twig
index 7abc8b6759..2dc829a4dd 100644
--- a/webapp/templates/jury/partials/team_score_and_submissions.html.twig
+++ b/webapp/templates/jury/partials/team_score_and_submissions.html.twig
@@ -8,7 +8,7 @@
     Submissions
     {% if restrictionText %}
     <small class="text-muted">
-        restricted to {{ restrictionText }} (<a href="{{ path('jury_team', {'teamId': team.teamid}) }}">show all</a>)
+        restricted to {{ restrictionText }} (<a href="{{ path('jury_team', {'teamId': team.externalid}) }}">show all</a>)
     </small>
     {% endif %}
 </h2>
diff --git a/webapp/templates/jury/problem.html.twig b/webapp/templates/jury/problem.html.twig
index 0679104872..1b29b98ce6 100644
--- a/webapp/templates/jury/problem.html.twig
+++ b/webapp/templates/jury/problem.html.twig
@@ -1,7 +1,7 @@
 {% extends "jury/base.html.twig" %}
 {% import "jury/jury_macros.twig" as macros %}
 
-{% block title %}Problem {{ problem.probid }} - {{ parent() }}{% endblock %}
+{% block title %}Problem {{ problem.externalid }} - {{ parent() }}{% endblock %}
 
 {% block extrahead %}
     {{ parent() }}
@@ -19,10 +19,6 @@
             <table class="table table-sm table-striped">
                 <tr>
                     <th>ID</th>
-                    <td>p{{ problem.probid }}</td>
-                </tr>
-                <tr>
-                    <th>External ID</th>
                     <td>{{ problem.externalid }}</td>
                 </tr>
                 <tr>
@@ -33,8 +29,8 @@
                         {% else %}
                             {{ problem.testcases.count }}
                         {% endif %}
-                        <a href="{{ path('jury_problem_testcases', {'probId': problem.probid}) }}">details
-                            {%- if is_granted('ROLE_ADMIN') and not lockedProblem -%}
+                        <a href="{{ path('jury_problem_testcases', {'probId': problem.externalid}) }}">details
+                            {%- if is_granted('ROLE_ADMIN') and not lockedProblem %}
                                 / edit
                             {% endif %}
                         </a>
@@ -68,7 +64,7 @@
                     <tr>
                         <th>Problem statement</th>
                         <td>
-                            <a href="{{ path('jury_problem_statement', {'probId': problem.probid}) }}">
+                            <a href="{{ path('jury_problem_statement', {'probId': problem.externalid}) }}">
                                 <i title="view problem statement"
                                    class="fas fa-file-{{ problem.problemstatementType }}"></i>
                             </a>
@@ -124,7 +120,7 @@
                         {% else %}
                             <ul>
                                 {% for language in problem.languages %}
-                                    <li><a href="{{ path('jury_language', {'langId': language.langid}) }}">{{ language.name }}</a></li>
+                                    <li><a href="{{ path('jury_language', {'langId': language.externalid}) }}">{{ language.name }}</a></li>
                                 {% endfor %}
                             </ul>
                         {% endif %}
@@ -137,13 +133,13 @@
     <div class="button-row">
         {%- if is_granted('ROLE_ADMIN') -%}
             {%- if not lockedProblem -%}
-                {{ button(path('jury_problem_edit', {'probId': problem.probid}), 'Edit', 'primary', 'edit') }}
-                {{ button(path('jury_problem_delete', {'probId': problem.probid}), 'Delete', 'danger', 'trash-alt', true) }}
+                {{ button(path('jury_problem_edit', {'probId': problem.externalid}), 'Edit', 'primary', 'edit') }}
+                {{ button(path('jury_problem_delete', {'probId': problem.externalid}), 'Delete', 'danger', 'trash-alt', true) }}
             {% endif %}
-            {{ button(path('jury_problem_request_remaining', {'probId': problem.probid}), 'Judge remaining testcases', 'secondary', 'gavel') }}
+            {{ button(path('jury_problem_request_remaining', {'probId': problem.externalid}), 'Judge remaining testcases', 'secondary', 'gavel') }}
         {% endif %}
-        {{ button(path('jury_export_problem', {'problemId': problem.probid}), 'Export', 'secondary', 'download') }}
-        {% include 'jury/partials/rejudge_form.html.twig' with {table: 'problem', id: problem.probid, buttonClass: 'btn-secondary'} %}
+        {{ button(path('jury_export_problem', {'problemId': problem.externalid}), 'Export', 'secondary', 'download') }}
+        {% include 'jury/partials/rejudge_form.html.twig' with {table: 'problem', id: problem.externalid, buttonClass: 'btn-secondary'} %}
     </div>
 
     <h3>Contests</h3>
@@ -157,7 +153,7 @@
                     class="data-table table table-hover table-striped table-sm">
                     <thead class="thead-light">
                     <tr>
-                        <th>CID</th>
+                        <th>ID</th>
                         <th>Contest<br/>shortname</th>
                         <th>Contest<br/>name</th>
                         <th>Problem<br/>shortname</th>
@@ -168,10 +164,10 @@
                     </thead>
                     <tbody>
                     {% for contestProblem in problem.contestProblems %}
-                        {% set link = path('jury_contest', {'contestId': contestProblem.cid}) %}
+                        {% set link = path('jury_contest', {'contestId': contestProblem.contest.externalid}) %}
                         <tr>
                             <td>
-                                <a href="{{ link }}">c{{ contestProblem.cid }}</a>
+                                <a href="{{ link }}">{{ contestProblem.contest.externalid }}</a>
                             </td>
                             <td>
                                 <a href="{{ link }}">{{ contestProblem.contest.shortname }}</a>
diff --git a/webapp/templates/jury/problem_edit.html.twig b/webapp/templates/jury/problem_edit.html.twig
index 0c1e7efa3c..13b04caa48 100644
--- a/webapp/templates/jury/problem_edit.html.twig
+++ b/webapp/templates/jury/problem_edit.html.twig
@@ -1,7 +1,7 @@
 {% extends "jury/base.html.twig" %}
 {% import "jury/jury_macros.twig" as macros %}
 
-{% block title %}Edit problem {{ problem.probid }} - {{ parent() }}{% endblock %}
+{% block title %}Edit problem {{ problem.externalid }} - {{ parent() }}{% endblock %}
 
 {% block content %}
 
@@ -10,17 +10,13 @@
     <div class="row">
         <div class="col-lg-4">
             <table class="table table-sm table-striped">
-                <tr>
-                    <th>Problem ID</th>
-                    <td>{{ problem.probid }}</td>
-                </tr>
                 <tr>
                     <th>Testcases</th>
                     <td>
                         {% if problem.testcases is empty %}
                             <em>no testcases</em>
                         {% else %}
-                            <a href="{{ path('jury_problem_testcases', {'probId': problem.probid}) }}">details / edit</a>
+                            <a href="{{ path('jury_problem_testcases', {'probId': problem.externalid}) }}">details / edit</a>
                         {% endif %}
                     </td>
                 </tr>
diff --git a/webapp/templates/jury/problem_testcases.html.twig b/webapp/templates/jury/problem_testcases.html.twig
index 8a54121fb8..24808df9a1 100644
--- a/webapp/templates/jury/problem_testcases.html.twig
+++ b/webapp/templates/jury/problem_testcases.html.twig
@@ -1,7 +1,7 @@
 {% extends "jury/base.html.twig" %}
 {% import "jury/jury_macros.twig" as macros %}
 
-{% block title %}Testcases for p{{ problem.probid }} - {{ parent() }}{% endblock %}
+{% block title %}Testcases for p{{ problem.externalid }} - {{ parent() }}{% endblock %}
 
 {% block extrahead %}
     {{ parent() }}
@@ -10,10 +10,10 @@
 
 {% block content %}
 
-    <h1>Testcases for p{{ problem.probid }} - {{ problem.name }}</h1>
+    <h1>Testcases for {{ problem.externalid }} - {{ problem.name }}</h1>
 
     <div class="mb-2">
-        <a href="{{ path('jury_problem', {'probId': problem.probid}) }}">Back to problem p{{ problem.probid }}</a>
+        <a href="{{ path('jury_problem', {'probId': problem.externalid}) }}">Back to problem {{ problem.externalid }}</a>
     </div>
 
     <form method="post" enctype="multipart/form-data">
diff --git a/webapp/templates/jury/refresh_cache.html.twig b/webapp/templates/jury/refresh_cache.html.twig
index c9216004f7..e7525f59d5 100644
--- a/webapp/templates/jury/refresh_cache.html.twig
+++ b/webapp/templates/jury/refresh_cache.html.twig
@@ -32,7 +32,7 @@
             </p>
             <form action="{{ path('jury_refresh_cache') }}" method="post">
                 {% if current_contest is not empty %}
-                    <input type="hidden" name="cid" value="{{ current_contest.cid }}"/>
+                    <input type="hidden" name="cid" value="{{ current_contest.externalid }}"/>
                 {% endif %}
                 <button type="submit" class="btn btn-danger" name="refresh">
                     <i class="fas fa-sync-alt"></i> Refresh now!
@@ -46,7 +46,7 @@
     {% if doRefresh %}
         {% set progressUrl = path('jury_refresh_cache') %}
         {% if current_contest is not empty %}
-            {% set progressUrl = progressUrl ~ '?cid=' ~ current_contest.cid %}
+            {% set progressUrl = progressUrl ~ '?cid=' ~ current_contest.externalid %}
         {% endif %}
         {{ macros.progress_loader(progressUrl) }}
     {% endif %}
diff --git a/webapp/templates/jury/submission.html.twig b/webapp/templates/jury/submission.html.twig
index 18f31720e9..f41b5eafce 100644
--- a/webapp/templates/jury/submission.html.twig
+++ b/webapp/templates/jury/submission.html.twig
@@ -1,7 +1,7 @@
 {# @var \App\Entity\ExternalJudgement externalJudgement #}
 {% extends "jury/base.html.twig" %}
 
-{% block title %}Submission s{{ submission.submitid }} - {{ parent() }}{% endblock %}
+{% block title %}Submission {{ submission.externalid }} - {{ parent() }}{% endblock %}
 
 {% block extrahead %}
     {{ parent() }}
@@ -75,7 +75,7 @@
         {% for type, versions in version_warnings %}
             <div class="alert alert-warning">
                 <p>
-                    This judging did not use the same {{ type}} version for all testcases.
+                    This judging did not use the same {{ type }} version for all testcases.
                     This may lead to unexpected results. Versions used:
                 </p>
                 <p>
@@ -91,16 +91,16 @@
     <div class="card">
         <div class="card-header">
             <h1 style="display: inline;">
-                Submission s{{ submission.submitid }}
+                Submission {{ submission.externalid }}
                 {% if submission.originalSubmission %}
-                    {% set origSubmissionUrl = path('jury_submission', {submitId: submission.originalSubmission.submitid}) %}
-                    (resubmit of <a href="{{ origSubmissionUrl }}">s{{ submission.originalSubmission.submitid }}</a>)
+                    {% set origSubmissionUrl = path('jury_submission', {submitId: submission.originalSubmission.externalid}) %}
+                    (resubmit of <a href="{{ origSubmissionUrl }}">{{ submission.originalSubmission.externalid }}</a>)
                 {% endif %}
                 {% if submission.resubmissions is not empty %}
                     (resubmitted as
                     {%- for resubmission in submission.resubmissions -%}
-                        {% set resubmissionUrl = path('jury_submission', {submitId: resubmission.submitid}) %}
-                        <a href="{{ resubmissionUrl }}">s{{ resubmission.submitid }}</a>
+                        {% set resubmissionUrl = path('jury_submission', {submitId: resubmission.externalid}) %}
+                        <a href="{{ resubmissionUrl }}">{{ resubmission.externalid }}</a>
                         {%- if not loop.last -%},{%- endif -%}
                     {%- endfor -%}
                     )
@@ -117,16 +117,16 @@
                         {% else %}
                             {% set action = 'unignore' %}
                         {% endif %}
-                        <form action="{{ path('jury_submission_update_status', {'submitId': submission.submitid}) }}" method="post"
+                        <form action="{{ path('jury_submission_update_status', {'submitId': submission.externalid}) }}" method="post"
                               style="display: inline; ">
                             <input type="hidden" name="valid" value="{% if submission.valid %}0{% else %}1{% endif %}"/>
                             <input type="submit" class="btn btn-outline-secondary btn-sm"
                                    value="{{ action | upper }} this submission"
-                                   onclick="return confirm('Really {{ action }} submission s{{ submission.submitid }}?');"/>
+                                   onclick="return confirm('Really {{ action }} submission {{ submission.externalid }}?');"/>
                         </form>
                     {% endif %}
 
-                    {% include 'jury/partials/rejudge_form.html.twig' with {table: 'submission', id: submission.submitid} %}
+                    {% include 'jury/partials/rejudge_form.html.twig' with {table: 'submission', id: submission.externalid} %}
                 </div>
             {% endif %}
 
@@ -134,16 +134,16 @@
             <div class="submission-summary mb-2">
                 <span>
                     <i class="fas fa-users" title="Team:"></i>
-                    <a href="{{ path('jury_team', {teamId: submission.team.teamid, cid: submission.contest.cid}) }}">
-                        {{ submission.team.effectiveName }} {{ submission.team | entityIdBadge('t') }}
+                    <a href="{{ path('jury_team', {teamId: submission.team.externalid, cid: submission.contest.externalid}) }}">
+                        {{ submission.team.effectiveName }} {{ submission.team | entityIdBadge }}
                     </a>
                 </span>
 
                 {% if submission.user %}
                     <span>
                         <i class="fas fa-user" title="User:"></i>
-                        <a href="{{ path('jury_user', {userId: submission.user.userid, cid: submission.contest.cid}) }}">
-                            {{ submission.user.username }} {{ submission.user | entityIdBadge('u') }}
+                        <a href="{{ path('jury_user', {userId: submission.user.externalid, cid: submission.contest.externalid}) }}">
+                            {{ submission.user.username }} {{ submission.user | entityIdBadge }}
                         </a>
                     </span>
                 {% endif %}
@@ -151,28 +151,28 @@
                 {% if current_contest.cid != submission.contest.cid %}
                     <span>
                         <i class="fas fa-trophy" title="Contest:"></i>
-                        <a href="{{ path('jury_contest', {'contestId': submission.contest.cid}) }}">
+                        <a href="{{ path('jury_contest', {'contestId': submission.contest.externalid}) }}">
                             {{ submission.contest.shortname }}
-                            {{ submission.contest | entityIdBadge('c') }}
+                            {{ submission.contest | entityIdBadge }}
                         </a>
                     </span>
                 {% endif %}
 
                 <span>
                     <i class="fas fa-book-open" title="Problem:"></i>
-                    <a href="{{ path('jury_problem', {'probId': submission.problem.probid}) }}">
+                    <a href="{{ path('jury_problem', {'probId': submission.problem.externalid}) }}">
                         {% if submission.contestProblem %}
                             {{ submission.contestProblem | problemBadge }} {{ submission.problem.name }}
                         {% else %}
                             {{ submission.problem.name }}
                         {% endif %}
-                        {{ submission.problem | entityIdBadge('p') }}
+                        {{ submission.problem | entityIdBadge }}
                     </a>
                 </span>
 
                 <span>
                     <i class="fas fa-comments" title="Language:"></i>
-                    <a href="{{ path('jury_language', {'langId': submission.language.langid}) }}">
+                    <a href="{{ path('jury_language', {'langId': submission.language.externalid}) }}">
                         {{ submission.language.name }}
                         {{ submission.language | entityIdBadge }}
                     </a>
@@ -192,25 +192,20 @@
 
                 <span>
                     <i class="fas fa-code" title="Source code:"></i>
-                    <a href="{{ path('jury_submission_source', {submission: submission.submitid}) }}">
+                    <a href="{{ path('jury_submission_source', {submission: submission.externalid}) }}">
                         View {{ submission.files | printFiles }}
                     </a>
                 </span>
 
-                {% if shadowMode() and submission.externalid %}
-                    {% if external_ccs_submission_url is empty %}
-                        External ID: {{- submission.externalid -}}
-                    {% else %}
-                        {% set externalSubmissionUrl = submission | externalCcsUrl %}
-                        {% if externalSubmissionUrl is not empty %}
-                            <span>
-                                <i class="fas fa-link" title="External link:"></i>
-                                <a href="{{ externalSubmissionUrl }}" target="_blank">
-                                    View in external CCS
-                                </a>
-                                (ID: {{- submission.externalid -}})
-                            </span>
-                        {% endif %}
+                {% if shadowMode() and external_ccs_submission_url is not empty %}
+                    {% set externalSubmissionUrl = submission | externalCcsUrl %}
+                    {% if externalSubmissionUrl is not empty %}
+                        <span>
+                            <i class="fas fa-link" title="External link:"></i>
+                            <a href="{{ externalSubmissionUrl }}" target="_blank">
+                                View in external CCS
+                            </a>
+                        </span>
                     {% endif %}
                 {% endif %}
             </div>
@@ -288,7 +283,7 @@
             </thead>
             <tbody>
             {% for judging in judgings %}
-                {% set link = path('jury_submission', {submitId: submission.submitid, jid: judging.judgingid}) %}
+                {% set link = path('jury_submission', {submitId: submission.externalid, jid: judging.judgingid}) %}
                 <tr {% if not judging.valid %}class="disabled"{% endif %}>
                     <td>
                         <a href="{{ link }}">
@@ -372,9 +367,9 @@
                             {%- endif -%}
                         {% endif %}
                         {%- if lastJudging is not null -%}
-                            {% set lastSubmissionLink = path('jury_submission', {submitId: lastSubmission.submitid}) %}{#-
+                            {% set lastSubmissionLink = path('jury_submission', {submitId: lastSubmission.externalid}) %}{#-
                         -#}<span class="lastresult">
-                            (<a href="{{ lastSubmissionLink }}">s{{ lastSubmission.submitid }}</a>: {{ lastJudging.result | printResult }}){#-
+                            (<a href="{{ lastSubmissionLink }}">{{ lastSubmission.externalid }}</a>: {{ lastJudging.result | printResult }}){#-
                         -#}</span>
                         {%- endif -%}
                         {%- if externalJudgement is not null %}
@@ -433,7 +428,7 @@
                     {% endif %}
                 &nbsp;
                 {% if not selectedJudging.verified %}
-                    <form action="{{ path('jury_submission', {submitId: submission.submitid, jid: selectedJudging.judgingid}) }}"
+                    <form action="{{ path('jury_submission', {submitId: submission.externalid, jid: selectedJudging.judgingid}) }}"
                           method="post" style="display: inline;">
                         {% if selectedJudging.juryMember is not empty %}
                             (claimed by {{ selectedJudging.juryMember }})
@@ -449,7 +444,7 @@
                 &nbsp;
                 {% if selectedJudging is null or selectedJudging.result is empty %}
                     {%- if not selectedJudging or not selectedJudging.started %}
-                        <a href="{{ path('jury_submission_create_tasks', {'submitId': submission.submitid}) }}">
+                        <a href="{{ path('jury_submission_create_tasks', {'submitId': submission.externalid}) }}">
                             <button class="btn btn-sm btn-outline-secondary" >
                                 <i class="fas fa-gavel"></i>
                                 Judge submission
@@ -562,7 +557,7 @@
                                 {{ lastRuns | displayTestcaseResults(lastJudging.endtime is not empty) }}
                             </td>
                             <td>
-                                <a href="{{ lastSubmissionLink }}">previous s{{ lastSubmission.submitid }}</a>
+                                <a href="{{ lastSubmissionLink }}">previous {{ lastSubmission.externalid }}</a>
                                 {% if lastJudging.verifyComment %}
                                     <span class="prevsubmit">(verify comment: '{{ lastJudging.verifyComment }}')</span>
                                 {% endif %}
@@ -671,20 +666,20 @@
                             -#}<button type="button" class="btn btn-link" onclick="navigator.clipboard.writeText('{{ runsOutput[runIdx].testcasedir }}')"><i class="fa-regular fa-copy"></i></button>
                         {% endif %}
                         <div style="float: right;">
-                            <a href="{{ path('jury_problem_testcase_fetch', {'probId': submission.problem.probid, 'rank': run.rank, 'type': 'input'}) }}">
+                            <a href="{{ path('jury_problem_testcase_fetch', {'probId': submission.problem.externalid, 'rank': run.rank, 'type': 'input'}) }}">
                                 <button class="btn btn-sm btn-outline-secondary" >
                                     <i class="fas fa-download"></i>
                                     Input
                                 </button>
                             </a>
-                            <a href="{{ path('jury_problem_testcase_fetch', {'probId': submission.problem.probid, 'rank': run.rank, 'type': 'output'}) }}">
+                            <a href="{{ path('jury_problem_testcase_fetch', {'probId': submission.problem.externalid, 'rank': run.rank, 'type': 'output'}) }}">
                                 <button class="btn btn-sm btn-outline-secondary" >
                                     <i class="fas fa-download"></i>
                                     Reference Output
                                 </button>
                             </a>
                             {% if run.firstJudgingRun is not null %}
-                                <a href="{{ path('jury_submission_team_output', {'submission': submission.submitid, 'run': run.firstJudgingRun.runid, 'contest': submission.contest.cid}) }}">
+                                <a href="{{ path('jury_submission_team_output', {'submission': submission.externalid, 'run': run.firstJudgingRun.runid, 'contest': submission.contest.externalid}) }}">
                                     <button class="btn btn-sm btn-outline-secondary" >
                                         <i class="fas fa-download"></i>
                                         {% if runsOutput[runIdx].is_output_run_truncated_in_db %}
@@ -735,7 +730,7 @@
                     {% endif %}
                     {% if runsOutput[runIdx].image_thumb %}
                         <span style="float:right; border: 3px solid #438ec3; margin: 5px; padding: 5px;">
-                            {% set imgUrl = path('jury_problem_testcase_fetch', {'probId': submission.problem.probid, 'rank': run.rank, 'type': 'image'}) %}
+                            {% set imgUrl = path('jury_problem_testcase_fetch', {'probId': submission.problem.externalid, 'rank': run.rank, 'type': 'image'}) %}
                             <a href="{{ imgUrl }}">
                                 <img class="image_thumb" src="data:{{ run.imageType | extensionToMime }};base64,{{ runsOutput[runIdx].image_thumb | base64 }}"/>
                             </a>
diff --git a/webapp/templates/jury/submission_edit_source.html.twig b/webapp/templates/jury/submission_edit_source.html.twig
index c280b8ed15..420c5f5cc1 100644
--- a/webapp/templates/jury/submission_edit_source.html.twig
+++ b/webapp/templates/jury/submission_edit_source.html.twig
@@ -1,13 +1,13 @@
 {% extends "jury/base.html.twig" %}
 {% import "jury/jury_macros.twig" as macros %}
 
-{% block title %}Edit source of s{{ submission.submitid }} - {{ parent() }}{% endblock %}
+{% block title %}Edit source of {{ submission.externalid }} - {{ parent() }}{% endblock %}
 
 {% block content %}
 
     <h1>
         Edit submission
-        <a href="{{ path('jury_submission', {submitId: submission.submitid}) }}">s{{ submission.submitid }}</a>
+        <a href="{{ path('jury_submission', {submitId: submission.externalid}) }}">{{ submission.externalid }}</a>
         source files
     </h1>
 
diff --git a/webapp/templates/jury/submission_source.html.twig b/webapp/templates/jury/submission_source.html.twig
index dd12005926..fda90dda22 100644
--- a/webapp/templates/jury/submission_source.html.twig
+++ b/webapp/templates/jury/submission_source.html.twig
@@ -1,25 +1,25 @@
 {% extends "jury/base.html.twig" %}
 {% import "jury/jury_macros.twig" as macros %}
 
-{% block title %}Source s{{ submission.submitid }} - {{ parent() }}{% endblock %}
+{% block title %}Source {{ submission.externalid }} - {{ parent() }}{% endblock %}
 
 {% block extrahead %}
     {{ parent() }}
 {% endblock %}
 
 {% block content %}
-    {% set editor_id = "diffw" ~ submission.submitid %}
+    {% set editor_id = "diffw" ~ submission.externalid %}
     <h1>
         Source code for submission
-        <a href="{{ path('jury_submission', {submitId: submission.submitid}) }}">s{{ submission.submitid }}</a>
+        <a href="{{ path('jury_submission', {submitId: submission.externalid}) }}">{{ submission.externalid }}</a>
         {%- if submission.originalSubmission %}
             (resubmit of
-            <a href="{{ path('jury_submission', {submitId: submission.originalSubmission.submitid}) }}">s{{ submission.originalSubmission.submitid }}</a>)
+            <a href="{{ path('jury_submission', {submitId: submission.originalSubmission.externalid}) }}">{{ submission.originalSubmission.externalid }}</a>)
         {%- endif %}
         {% if submission.resubmissions is not empty %}
             (resubmitted as
             {%- for resubmission in submission.resubmissions %}
-                <a href="{{ path('jury_submission', {submitId: resubmission.originalSubmission.submitid}) }}">s{{ resubmission.submitid }}</a>
+                <a href="{{ path('jury_submission', {submitId: resubmission.originalSubmission.externalid}) }}">{{ resubmission.externalid }}</a>
                 {%- if not loop.last -%},{%- endif -%}
             {%- endfor -%}
             )
diff --git a/webapp/templates/jury/team.html.twig b/webapp/templates/jury/team.html.twig
index 8db6ef1f1b..76b789d7b9 100644
--- a/webapp/templates/jury/team.html.twig
+++ b/webapp/templates/jury/team.html.twig
@@ -1,7 +1,7 @@
 {% extends "jury/base.html.twig" %}
 {% import "jury/jury_macros.twig" as macros %}
 
-{% block title %}Team {{ team.teamid }} - {{ parent() }}{% endblock %}
+{% block title %}Team {{ team.externalid }} - {{ parent() }}{% endblock %}
 
 {% block extrahead %}
     {{ parent() }}
@@ -18,10 +18,6 @@
             <table class="table table-sm table-striped">
                 <tr>
                     <th>ID</th>
-                    <td>{{ team.teamid }}</td>
-                </tr>
-                <tr>
-                    <th>External ID</th>
                     <td>{{ team.externalid }}</td>
                 </tr>
                 <tr>
@@ -94,10 +90,10 @@
                     <th>User</th>
                     <td>
                         {% for user in team.users %}
-                            <a href="{{ path('jury_user', {'userId': user.userid}) }}">{{ user.username }}</a>
+                            <a href="{{ path('jury_user', {'userId': user.externalid}) }}">{{ user.username }}</a>
                         {% else %}
                             {%- if is_granted('ROLE_ADMIN') -%}
-                                <a href="{{ path('jury_user_add', {'team': team.teamid}) }}">
+                                <a href="{{ path('jury_user_add', {'team': team.externalid}) }}">
                                     <i class="fas fa-user-plus"></i> add user
                                 </a>
                             {% endif %}
@@ -113,7 +109,7 @@
                     <th>Category</th>
                     <td>
                         {% if team.category %}
-                            <a href="{{ path('jury_team_category', {'categoryId': team.category.categoryid}) }}">
+                            <a href="{{ path('jury_team_category', {'categoryId': team.category.externalid}) }}">
                                 {{ team.category.name }}
                             </a>
                         {% else %}
@@ -131,7 +127,7 @@
                                 <img src="{{ asset(affiliationLogo) }}" alt="{{ team.affiliation.shortname }}"
                                      title="{{ team.affiliation.shortname }}" class="affiliation-logo"/>
                             {% endif %}
-                            <a href="{{ path('jury_team_affiliation', {'affilId': team.affiliation.affilid}) }}">
+                            <a href="{{ path('jury_team_affiliation', {'affilId': team.affiliation.externalid}) }}">
                                 {{ team.affiliation.name }}
                             </a>
                         </td>
@@ -150,7 +146,7 @@
                     <th>Contests</th>
                     <td>
                         {% for ucontest in team.contests %}
-                            <a href="{{ path('jury_contest', {'contestId': ucontest.cid}) }}">{{ ucontest.shortname }}</a>
+                            <a href="{{ path('jury_contest', {'contestId': ucontest.externalid}) }}">{{ ucontest.shortname }}</a>
                         {% endfor %}
                     </td>
                 </tr>
@@ -183,11 +179,11 @@
 
     <div class="button-row">
         {%- if is_granted('ROLE_ADMIN') -%}
-            {{ button(path('jury_team_edit', {'teamId': team.teamid}), 'Edit', 'primary', 'edit') }}
-            {{ button(path('jury_team_delete', {'teamId': team.teamid}), 'Delete', 'danger', 'trash-alt', true) }}
+            {{ button(path('jury_team_edit', {'teamId': team.externalid}), 'Edit', 'primary', 'edit') }}
+            {{ button(path('jury_team_delete', {'teamId': team.externalid}), 'Delete', 'danger', 'trash-alt', true) }}
         {% endif %}
-        {{ button(path('jury_clarification_new', {'teamto': team.teamid}), 'Send message', 'secondary', 'envelope') }}
-        {% include 'jury/partials/rejudge_form.html.twig' with {table: 'team', id: team.teamid, buttonClass: 'btn-secondary'} %}
+        {{ button(path('jury_clarification_new', {'teamto': team.externalid}), 'Send message', 'secondary', 'envelope') }}
+        {% include 'jury/partials/rejudge_form.html.twig' with {table: 'team', id: team.externalid, buttonClass: 'btn-secondary'} %}
     </div>
 
     <div data-ajax-refresh-target>
diff --git a/webapp/templates/jury/team_affiliation.html.twig b/webapp/templates/jury/team_affiliation.html.twig
index 1de78a3446..3fefd282de 100644
--- a/webapp/templates/jury/team_affiliation.html.twig
+++ b/webapp/templates/jury/team_affiliation.html.twig
@@ -1,7 +1,7 @@
 {% extends "jury/base.html.twig" %}
 {% import "jury/jury_macros.twig" as macros %}
 
-{% block title %}Affiliation {{ teamAffiliation.affilid }} - {{ parent() }}{% endblock %}
+{% block title %}Affiliation {{ teamAffiliation.externalid }} - {{ parent() }}{% endblock %}
 
 {% block extrahead %}
     {{ parent() }}
@@ -17,10 +17,6 @@
             <table class="table table-sm table-striped">
                 <tr>
                     <th>ID</th>
-                    <td>{{ teamAffiliation.affilid }}</td>
-                </tr>
-                <tr>
-                    <th>External ID</th>
                     <td>{{ teamAffiliation.externalid }}</td>
                 </tr>
                 <tr>
@@ -70,8 +66,8 @@
 
     {%- if is_granted('ROLE_ADMIN') -%}
         <p>
-            {{ button(path('jury_team_affiliation_edit', {'affilId': teamAffiliation.affilid}), 'Edit', 'primary', 'edit') }}
-            {{ button(path('jury_team_affiliation_delete', {'affilId': teamAffiliation.affilid}), 'Delete', 'danger', 'trash-alt', true) }}
+            {{ button(path('jury_team_affiliation_edit', {'affilId': teamAffiliation.externalid}), 'Edit', 'primary', 'edit') }}
+            {{ button(path('jury_team_affiliation_delete', {'affilId': teamAffiliation.externalid}), 'Delete', 'danger', 'trash-alt', true) }}
         </p>
     {% endif %}
 
@@ -92,10 +88,10 @@
                     {% for team in teamAffiliation.teams %}
                         <tr>
                             <td style="text-align: right;">
-                                <a href="{{ path('jury_team', {'teamId': team.teamid}) }}">{{ team | entityIdBadge('t') }}</a>
+                                <a href="{{ path('jury_team', {'teamId': team.externalid}) }}">{{ team | entityIdBadge }}</a>
                             </td>
                             <td>
-                                <a href="{{ path('jury_team', {'teamId': team.teamid}) }}">{{ team.effectiveName }}</a>
+                                <a href="{{ path('jury_team', {'teamId': team.externalid}) }}">{{ team.effectiveName }}</a>
                             </td>
                         </tr>
                     {% endfor %}
diff --git a/webapp/templates/jury/team_affiliation_edit.html.twig b/webapp/templates/jury/team_affiliation_edit.html.twig
index ab73b36913..667a439ca5 100644
--- a/webapp/templates/jury/team_affiliation_edit.html.twig
+++ b/webapp/templates/jury/team_affiliation_edit.html.twig
@@ -1,6 +1,6 @@
 {% extends "jury/base.html.twig" %}
 
-{% block title %}Edit affiliation {{ teamAffiliation.affilid }} - {{ parent() }}{% endblock %}
+{% block title %}Edit affiliation {{ teamAffiliation.externalid }} - {{ parent() }}{% endblock %}
 
 {% import "jury/jury_macros.twig" as macros %}
 {% block extrahead %}
@@ -10,7 +10,7 @@
 
 {% block content %}
 
-    <h1>Edit affiliation {{ teamAffiliation.affilid }}</h1>
+    <h1>Edit affiliation {{ teamAffiliation.externalid }}</h1>
 
     {% include 'jury/partials/team_affiliation_form.html.twig' %}
 
diff --git a/webapp/templates/jury/team_category.html.twig b/webapp/templates/jury/team_category.html.twig
index 22b2790610..ef51c7d406 100644
--- a/webapp/templates/jury/team_category.html.twig
+++ b/webapp/templates/jury/team_category.html.twig
@@ -1,7 +1,7 @@
 {% extends "jury/base.html.twig" %}
 {% import "jury/jury_macros.twig" as macros %}
 
-{% block title %}Category {{ teamCategory.categoryid }} - {{ parent() }}{% endblock %}
+{% block title %}Category {{ teamCategory.externalid }} - {{ parent() }}{% endblock %}
 
 {% block extrahead %}
     {{ parent() }}
@@ -18,10 +18,6 @@
             <table class="table table-sm table-striped">
                 <tr>
                     <th>ID</th>
-                    <td>{{ teamCategory.categoryid }}</td>
-                </tr>
-                <tr>
-                    <th>External ID</th>
                     <td>{{ teamCategory.externalid }}</td>
                 </tr>
                 <tr>
@@ -58,9 +54,9 @@
 
     {%- if is_granted('ROLE_ADMIN') -%}
         <p>
-            {{ button(path('jury_team_category_edit', {'categoryId': teamCategory.categoryid}), 'Edit', 'primary', 'edit') }}
-            {{ button(path('jury_team_category_delete', {'categoryId': teamCategory.categoryid}), 'Delete', 'danger', 'trash-alt', true) }}
-            {{ button(path('jury_team_category_request_remaining', {'categoryId': teamCategory.categoryid}), 'Judge remaining testcases', 'secondary', 'gavel') }}
+            {{ button(path('jury_team_category_edit', {'categoryId': teamCategory.externalid}), 'Edit', 'primary', 'edit') }}
+            {{ button(path('jury_team_category_delete', {'categoryId': teamCategory.externalid}), 'Delete', 'danger', 'trash-alt', true) }}
+            {{ button(path('jury_team_category_request_remaining', {'categoryId': teamCategory.externalid}), 'Judge remaining testcases', 'secondary', 'gavel') }}
         </p>
     {% endif %}
 
@@ -81,10 +77,10 @@
                     {% for team in teamCategory.teams %}
                         <tr>
                             <td style="text-align: right">
-                                <a href="{{ path('jury_team', {'teamId': team.teamid}) }}">{{ team | entityIdBadge('t') }}</a>
+                                <a href="{{ path('jury_team', {'teamId': team.externalid}) }}">{{ team | entityIdBadge }}</a>
                             </td>
                             <td>
-                                <a href="{{ path('jury_team', {'teamId': team.teamid}) }}">{{ team.effectiveName }}</a>
+                                <a href="{{ path('jury_team', {'teamId': team.externalid}) }}">{{ team.effectiveName }}</a>
                             </td>
                         </tr>
                     {% endfor %}
diff --git a/webapp/templates/jury/team_category_edit.html.twig b/webapp/templates/jury/team_category_edit.html.twig
index 6e5b839143..e2f145e791 100644
--- a/webapp/templates/jury/team_category_edit.html.twig
+++ b/webapp/templates/jury/team_category_edit.html.twig
@@ -1,7 +1,7 @@
 {% extends "jury/base.html.twig" %}
 {% import "jury/jury_macros.twig" as macros %}
 
-{% block title %}Edit category {{ teamCategory.categoryid }} - {{ parent() }}{% endblock %}
+{% block title %}Edit category {{ teamCategory.externalid }} - {{ parent() }}{% endblock %}
 
 {% block extrahead %}
     {{ parent() }}
@@ -10,7 +10,7 @@
 
 {% block content %}
 
-    <h1>Edit category {{ teamCategory.categoryid }}</h1>
+    <h1>Edit category {{ teamCategory.externalid }}</h1>
 
     {% include 'jury/partials/team_category_form.html.twig' %}
 
diff --git a/webapp/templates/jury/team_edit.html.twig b/webapp/templates/jury/team_edit.html.twig
index 6b814e5910..7aca607a00 100644
--- a/webapp/templates/jury/team_edit.html.twig
+++ b/webapp/templates/jury/team_edit.html.twig
@@ -1,7 +1,7 @@
 {% extends "jury/base.html.twig" %}
 {% import "jury/jury_macros.twig" as macros %}
 
-{% block title %}Edit team {{ team.teamid }} - {{ parent() }}{% endblock %}
+{% block title %}Edit team {{ team.externalid }} - {{ parent() }}{% endblock %}
 
 {% block extrahead %}
     {{ parent() }}
@@ -12,17 +12,6 @@
 
     <h1>Edit team {{ team.teamid }}</h1>
 
-    <div class="row">
-        <div class="col-lg-4">
-            <table class="table table-sm table-striped">
-                <tr>
-                    <th>Team ID</th>
-                    <td>{{ team.teamid }}</td>
-                </tr>
-            </table>
-        </div>
-    </div>
-
     {% include 'jury/partials/team_form.html.twig' %}
 
 {% endblock %}
diff --git a/webapp/templates/jury/user.html.twig b/webapp/templates/jury/user.html.twig
index a8a071a8f3..8a50ebf5a2 100644
--- a/webapp/templates/jury/user.html.twig
+++ b/webapp/templates/jury/user.html.twig
@@ -1,7 +1,7 @@
 {% extends "jury/base.html.twig" %}
 {% import "jury/jury_macros.twig" as macros %}
 
-{% block title %}User {{ user.userid }} - {{ parent() }}{% endblock %}
+{% block title %}User {{ user.externalid }} - {{ parent() }}{% endblock %}
 
 {% block extrahead %}
     {{ parent() }}
@@ -18,10 +18,6 @@
             <table class="table table-sm table-striped">
                 <tr>
                     <th>ID</th>
-                    <td>{{ user.userid }}</td>
-                </tr>
-                <tr>
-                    <th>External ID</th>
                     <td>{{ user.externalid }}</td>
                 </tr>
                 <tr>
@@ -78,8 +74,8 @@
                     <th>Team</th>
                     {% if user.team %}
                         <td class="teamid">
-                            <a href="{{ path('jury_team', {'teamId': user.team.teamid}) }}">
-                                {{ user.team.effectiveName }} {{ user.team | entityIdBadge('t') }}
+                            <a href="{{ path('jury_team', {'teamId': user.team.externalid}) }}">
+                                {{ user.team.effectiveName }} {{ user.team | entityIdBadge }}
                             </a>
                         </td>
                     {% else %}
@@ -137,10 +133,10 @@
 
     <div class="button-row">
         {%- if is_granted('ROLE_ADMIN') -%}
-            {{ button(path('jury_user_edit', {'userId': user.userid}), 'Edit', 'primary', 'edit') }}
-            {{ button(path('jury_user_delete', {'userId': user.userid}), 'Delete', 'danger', 'trash-alt', true) }}
+            {{ button(path('jury_user_edit', {'userId': user.externalid}), 'Edit', 'primary', 'edit') }}
+            {{ button(path('jury_user_delete', {'userId': user.externalid}), 'Delete', 'danger', 'trash-alt', true) }}
         {% endif %}
-        {% include 'jury/partials/rejudge_form.html.twig' with {table: 'user', id: user.userid, buttonClass: 'btn-secondary'} %}
+        {% include 'jury/partials/rejudge_form.html.twig' with {table: 'user', id: user.externalid, buttonClass: 'btn-secondary'} %}
     </div>
 
     <h2>Submissions for {{ user.name }}</h2>
diff --git a/webapp/templates/jury/user_edit.html.twig b/webapp/templates/jury/user_edit.html.twig
index 45477f7969..39338ebdad 100644
--- a/webapp/templates/jury/user_edit.html.twig
+++ b/webapp/templates/jury/user_edit.html.twig
@@ -1,7 +1,7 @@
 {% extends "jury/base.html.twig" %}
 {% import "jury/jury_macros.twig" as macros %}
 
-{% block title %}Edit user {{ user.userid }} - {{ parent() }}{% endblock %}
+{% block title %}Edit user {{ user.externalid }} - {{ parent() }}{% endblock %}
 
 {% block extrahead %}
     {{ parent() }}
@@ -10,15 +10,11 @@
 
 {% block content %}
 
-    <h1>Edit user {{ user.userid }}</h1>
+    <h1>Edit user {{ user.externalid }}</h1>
 
     <div class="row">
         <div class="col-lg-4">
             <table class="table table-sm table-striped">
-                <tr>
-                    <th>User ID</th>
-                    <td>{{ user.userid }}</td>
-                </tr>
                 <tr>
                     <th>Username</th>
                     <td class="teamid">{{ user.username }}</td>
diff --git a/webapp/templates/jury/versions.html.twig b/webapp/templates/jury/versions.html.twig
index 04e636226a..b3b7504c19 100644
--- a/webapp/templates/jury/versions.html.twig
+++ b/webapp/templates/jury/versions.html.twig
@@ -17,7 +17,7 @@
                 Language <code>{{ lang.language.langid }}</code>
                 {% if is_granted('ROLE_ADMIN') %}
                 <span style="float: right">
-                    {{ button(path('jury_language_edit', {'langId': lang.language.langid}), 'Edit version command(s)', 'primary btn-sm', 'edit') }}
+                    {{ button(path('jury_language_edit', {'langId': lang.language.externalid}), 'Edit version command(s)', 'primary btn-sm', 'edit') }}
                 </span>
                 {% endif %}
             </div>
diff --git a/webapp/templates/partials/javascript_language_detect.html.twig b/webapp/templates/partials/javascript_language_detect.html.twig
index 78d87c159d..ce36146c2f 100644
--- a/webapp/templates/partials/javascript_language_detect.html.twig
+++ b/webapp/templates/partials/javascript_language_detect.html.twig
@@ -5,7 +5,7 @@
                 {% for language in submission_languages %}
                 {% for extension in language.extensions %}
             case '{{ extension|lower }}':
-                return '{{ language.langid }}';
+                return '{{ language.externalid }}';
                 {% endfor %}
                 {% endfor %}
             default:
@@ -17,7 +17,7 @@
         switch (mainext) {
                 {% for language in submission_languages %}
                 {% if language.requireEntryPoint %}
-            case '{{ language.langid }}':
+            case '{{ language.externalid }}':
                 return '{{ language.entryPointDescription | default('Entry point') }}';
                 {% endif %}
                 {% endfor %}
diff --git a/webapp/templates/partials/menu_change_contest.html.twig b/webapp/templates/partials/menu_change_contest.html.twig
index 5f6e637201..9ec1f7ec2a 100644
--- a/webapp/templates/partials/menu_change_contest.html.twig
+++ b/webapp/templates/partials/menu_change_contest.html.twig
@@ -11,7 +11,7 @@
         {% endif %}
         {% for c in contests | filter(c => c != contest) %}
             <a class="dropdown-item"
-               href="{{ path(change_path, {'contestId': c.cid}) }}">{{ c.shortname }}</a>
+               href="{{ path(change_path, {'contestId': c.externalid}) }}">{{ c.shortname }}</a>
         {% endfor %}
     </div>
 </li>
diff --git a/webapp/templates/partials/problem_list.html.twig b/webapp/templates/partials/problem_list.html.twig
index e98ba39797..a28812f7ab 100644
--- a/webapp/templates/partials/problem_list.html.twig
+++ b/webapp/templates/partials/problem_list.html.twig
@@ -145,7 +145,7 @@
                                             {% endif %}
                                             {% if clarificationsCount > 0 %}
                                                 <a data-ajax-modal class="btn btn-secondary" role="button"
-                                                   href="{{ path('team_clarification_by_prob', {'probId': problem.probid}) }}">
+                                                   href="{{ path('team_clarification_by_prob', {'probId': problem.externalId}) }}">
                                                     <i class="fas fa-question-circle"></i>
                                                     {% if clarificationsCount > 0 %}
                                                         {% set badgeClass = 'text-bg-info' %}
@@ -163,7 +163,7 @@
 
                                             {% if problem.problem.problemstatementType is not empty %}
                                                 <a class="btn btn-secondary" role="button"
-                                                   href="{{ path(problem_statement_path, {'probId': problem.probid}) }}">
+                                                   href="{{ path(problem_statement_path, {'probId': problem.externalId}) }}">
                                                     <i class="fas fa-file-{{ problem.problem.problemstatementType }}"></i>
                                                     statement
                                                 </a>
@@ -171,7 +171,7 @@
 
                                             {% if numsamples > 0 %}
                                                 <a class="btn btn-secondary" role="button"
-                                                   href="{{ path(problem_sample_zip_path, {'probId': problem.probid}) }}">
+                                                   href="{{ path(problem_sample_zip_path, {'probId': problem.externalId}) }}">
                                                     <i class="fas fa-file-archive"></i> samples
                                                 </a>
                                             {% endif %}
@@ -183,7 +183,7 @@
                                                 {% for attachment in problem.problem.attachments %}
                                                     <li class="list-group-item">
                                                         <a class="btn btn-outline-secondary" role="button"
-                                                           href="{{ path(problem_attachment_path, {'probId': problem.probid, 'attachmentId': attachment.attachmentid}) }}">
+                                                           href="{{ path(problem_attachment_path, {'probId': problem.externalId, 'attachmentId': attachment.attachmentid}) }}">
                                                             <i class="{{ attachment.type | fileTypeIcon }}"></i> {{ attachment.name }}
                                                         </a>
                                                     </li>
diff --git a/webapp/templates/partials/scoreboard_summary.html.twig b/webapp/templates/partials/scoreboard_summary.html.twig
index 0400016b15..7c98801e2f 100644
--- a/webapp/templates/partials/scoreboard_summary.html.twig
+++ b/webapp/templates/partials/scoreboard_summary.html.twig
@@ -32,7 +32,7 @@
                 <td style="text-align: left;">
                     {% set link = null %}
                     {% if jury %}
-                        {% set link = path('jury_problem', {'probId': problem.probid}) %}
+                        {% set link = path('jury_problem', {'probId': problem.externalid}) %}
                     {% endif %}
                     <a {% if link %}href="{{ link }}"{% endif %}>
                         <i class="fas fa-thumbs-up fa-fw"></i>
diff --git a/webapp/templates/partials/scoreboard_table.html.twig b/webapp/templates/partials/scoreboard_table.html.twig
index 71b074da1d..d5720b9313 100644
--- a/webapp/templates/partials/scoreboard_table.html.twig
+++ b/webapp/templates/partials/scoreboard_table.html.twig
@@ -94,13 +94,13 @@
                 {% set target = '_self' %}
                 {% if not static %}
                     {% if jury %}
-                        {% set link = path('jury_problem', {'probId': problem.probid}) %}
+                        {% set link = path('jury_problem', {'probId': problem.externalid}) %}
                     {% elseif problem.problem.problemstatementType is not empty %}
                         {% if public %}
-                            {% set link = path('public_problem_statement', {probId: problem.probid}) %}
+                            {% set link = path('public_problem_statement', {probId: problem.externalid}) %}
                             {% set target = '_blank' %}
                         {% else %}
-                            {% set link = path('team_problem_statement', {probId: problem.probid}) %}
+                            {% set link = path('team_problem_statement', {probId: problem.externalid}) %}
                             {% set target = '_blank' %}
                         {% endif %}
                     {% endif %}
@@ -108,7 +108,7 @@
                 <th
                     title="problem {{ problem.problem.name }}"
                     scope="col"
-                    data-problem-external-id="{{ problem.externalid }}"
+                    data-problem-id="{{ problem.externalid }}"
                     data-problem-name="{{ problem.problem.name | escape('html_attr') }}"
                     data-problem-badge="{{ problem | problemBadge | escape('html_attr') }}"
                 >
@@ -156,7 +156,7 @@
         {% else %}
             {% set color = score.team.category.color %}
         {% endif %}
-        <tr class="{{ classes | join(' ') }}" data-team-id="{{ score.team.teamid }}" data-team-external-id="{{ score.team.externalid }}" data-team-name="{{ score.team.effectiveName | escape('html_attr') }}">
+        <tr class="{{ classes | join(' ') }}" data-team-id="{{ score.team.externalid }}" data-team-name="{{ score.team.effectiveName | escape('html_attr') }}">
             {% if enable_ranking %}
                 {% if medalsEnabled %}
                     <td class="no-border">
@@ -188,7 +188,7 @@
                     {% if score.team.affiliation %}
                         {% set link = null %}
                         {% if jury %}
-                            {% set link = path('jury_team_affiliation', {'affilId': score.team.affiliation.affilid}) %}
+                            {% set link = path('jury_team_affiliation', {'affilId': score.team.affiliation.externalid}) %}
                         {% endif %}
                         <a {% if link %}href="{{ link }}"{% endif %}>
                             {{ score.team.affiliation.country|countryFlag }}
@@ -201,7 +201,7 @@
                     {% if score.team.affiliation %}
                         {% set link = null %}
                         {% if jury %}
-                            {% set link = path('jury_team_affiliation', {'affilId': score.team.affiliation.affilid}) %}
+                            {% set link = path('jury_team_affiliation', {'affilId': score.team.affiliation.externalid}) %}
                         {% endif %}
                         <a {% if link %}href="{{ link }}"{% endif %}>
                             {% set affiliationId = score.team.affiliation.externalid %}
@@ -225,15 +225,15 @@
                 {% set extra = null %}
                 {% if static %}
                     {% set link = '#' %}
-                    {% set extra = 'data-bs-toggle="modal" data-bs-target="#team-modal-' ~ score.team.teamid ~ '"' %}
+                    {% set extra = 'data-bs-toggle="modal" data-bs-target="#team-modal-' ~ score.team.externalid ~ '"' %}
                 {% else %}
                     {% if jury %}
-                        {% set link = path('jury_team', {teamId: score.team.teamid}) %}
+                        {% set link = path('jury_team', {teamId: score.team.externalid}) %}
                     {% elseif public %}
-                        {% set link = path('public_team', {teamId: score.team.teamid}) %}
+                        {% set link = path('public_team', {teamId: score.team.externalid}) %}
                         {% set extra = 'data-ajax-modal' %}
                     {% else %}
-                        {% set link = path('team_team', {teamId: score.team.teamid}) %}
+                        {% set link = path('team_team', {teamId: score.team.externalid}) %}
                         {% set extra = 'data-ajax-modal' %}
                     {% endif %}
                 {% endif %}
@@ -321,8 +321,8 @@
                     {% set link = null %}
                     {% set extra = null %}
                     {% if jury %}
-                        {% set restrict = {problemId: problem.probid} %}
-                        {% set link = path('jury_team', {teamId: score.team.teamid, restrict: restrict}) %}
+                        {% set restrict = {problemId: problem.externalid} %}
+                        {% set link = path('jury_team', {teamId: score.team.externalid, restrict: restrict}) %}
                     {% elseif static %}
                         {% set link = '#' %}
                         {% set extra = 'data-submissions-url="' ~ path('public_submissions_data') ~ '"' %}
@@ -441,8 +441,7 @@
     {% endif %}
     <tr
         class="{{ classes | join(' ') }}"
-        data-team-id="{{ score.team.teamid }}"
-        data-team-external-id="{{ score.team.externalid }}"
+        data-team-id="{{ score.team.externalid }}"
         data-team-name="{{ score.team.effectiveName | escape('html_attr') }}"
         style="border-bottom-width: 0; height: 28px;">
         {% if enable_ranking %}
@@ -463,7 +462,7 @@
                 {% if score.team.affiliation %}
                     {% set link = null %}
                     {% if jury %}
-                        {% set link = path('jury_team_affiliation', {'affilId': score.team.affiliation.affilid}) %}
+                        {% set link = path('jury_team_affiliation', {'affilId': score.team.affiliation.externalid}) %}
                     {% endif %}
                     <a {% if link %}href="{{ link }}"{% endif %}>
                         {{ score.team.affiliation.country|countryFlag }}
@@ -476,7 +475,7 @@
                 {% if score.team.affiliation %}
                     {% set link = null %}
                     {% if jury %}
-                        {% set link = path('jury_team_affiliation', {'affilId': score.team.affiliation.affilid}) %}
+                        {% set link = path('jury_team_affiliation', {'affilId': score.team.affiliation.externalid}) %}
                     {% endif %}
                     <a {% if link %}href="{{ link }}"{% endif %}>
                         {% set affiliationId = score.team.affiliation.externalid %}
@@ -500,15 +499,15 @@
         {% set extra = null %}
         {% if static %}
             {% set link = '#' %}
-            {% set extra = 'data-bs-toggle="modal" data-bs-target="#team-modal-' ~ score.team.teamid ~ '"' %}
+            {% set extra = 'data-bs-toggle="modal" data-bs-target="#team-modal-' ~ score.team.externalid ~ '"' %}
         {% else %}
             {% if jury %}
-                {% set link = path('jury_team', {teamId: score.team.teamid}) %}
+                {% set link = path('jury_team', {teamId: score.team.externalid}) %}
             {% elseif public %}
-                {% set link = path('public_team', {teamId: score.team.teamid}) %}
+                {% set link = path('public_team', {teamId: score.team.externalid}) %}
                 {% set extra = 'data-ajax-modal' %}
             {% else %}
-                {% set link = path('team_team', {teamId: score.team.teamid}) %}
+                {% set link = path('team_team', {teamId: score.team.externalid}) %}
                 {% set extra = 'data-ajax-modal' %}
             {% endif %}
         {% endif %}
@@ -573,7 +572,7 @@
 
 {% if static %}
     {% for score in scores %}
-        {% embed 'partials/modal.html.twig' with {'modalId': 'team-modal-' ~ score.team.teamid} %}
+        {% embed 'partials/modal.html.twig' with {'modalId': 'team-modal-' ~ score.team.externalid} %}
             {% block title %}{{ score.team.effectiveName }}{% endblock %}
             {% block content %}
                 {% include 'partials/team.html.twig' with {size: 6, team: score.team} %}
@@ -605,7 +604,7 @@
                     <td>
                         {% set link = null %}
                         {% if jury %}
-                            {% set link = path('jury_team_category', {'categoryId': category.categoryid}) %}
+                            {% set link = path('jury_team_category', {'categoryId': category.externalid}) %}
                         {% endif %}
                         <a {% if link %}href="{{ link }}"{% endif %}>{{ category.name }}</a>
                     </td>
diff --git a/webapp/templates/team/partials/clarification.html.twig b/webapp/templates/team/partials/clarification.html.twig
index 5004e4c0d4..2d0fba6c9f 100644
--- a/webapp/templates/team/partials/clarification.html.twig
+++ b/webapp/templates/team/partials/clarification.html.twig
@@ -20,14 +20,14 @@
                 <div class="col-sm">
                     From:
                     {% if clarification.sender is not empty %}
-                        {{ clarification.sender.effectiveName }} (t{{ clarification.sender.teamid }})
+                        {{ clarification.sender.effectiveName }} ({{ clarification.sender.externalid }})
                     {% else %}
                         Jury
                     {% endif %}
                 </div>
                 <div class="col-sm">To:
                     {% if clarification.recipient is not empty %}
-                        {{ clarification.recipient.effectiveName }} (t{{ clarification.recipient.teamid }})
+                        {{ clarification.recipient.effectiveName }} ({{ clarification.recipient.externalid }})
                     {% elseif clarification.sender is not null %}
                         Jury
                     {% else %}
diff --git a/webapp/templates/team/partials/clarification_list.html.twig b/webapp/templates/team/partials/clarification_list.html.twig
index a8afe67896..15e731dc2c 100644
--- a/webapp/templates/team/partials/clarification_list.html.twig
+++ b/webapp/templates/team/partials/clarification_list.html.twig
@@ -17,7 +17,7 @@
         </thead>
         <tbody>
         {%- for clarification in clarifications %}
-            {%- set link = path('team_clarification', {clarId: clarification.clarid}) %}
+            {%- set link = path('team_clarification', {clarId: clarification.externalid}) %}
 
             <tr class="{% if team.unreadClarifications.contains(clarification) %}unseen{% endif %}">
                 <td>
diff --git a/webapp/templates/team/partials/submission.html.twig b/webapp/templates/team/partials/submission.html.twig
index c5c3d9445b..6240c7c905 100644
--- a/webapp/templates/team/partials/submission.html.twig
+++ b/webapp/templates/team/partials/submission.html.twig
@@ -53,7 +53,7 @@
         {% if allowDownload %}
             <div class="d-flex flex-row">
                 <div class="p-2">
-                    <a title="Download submission ZIP" aria-label="download submission zip" class="btn btn-primary" href="{{ path('team_submission_download', {'submitId': judging.submission.submitid}) }}">
+                    <a title="Download submission ZIP" aria-label="download submission zip" class="btn btn-primary" href="{{ path('team_submission_download', {'submitId': judging.submission.externalid}) }}">
                         <i class="fa fa-file-archive"></i> Download submission ZIP
                     </a>
                 </div>
diff --git a/webapp/templates/team/partials/submission_list.html.twig b/webapp/templates/team/partials/submission_list.html.twig
index 80c4bd2123..75eaaf45dd 100644
--- a/webapp/templates/team/partials/submission_list.html.twig
+++ b/webapp/templates/team/partials/submission_list.html.twig
@@ -23,7 +23,7 @@
         {%- for submission in submissions %}
             {% set link = null %}
             {% if (submission.submittime < current_team_contest.endtime or showTooLateResult) and submission.result and submission.judgings.first is not empty and submission.judgings.first.result is not empty and (not verificationRequired or submission.judgings.first.verified) %}
-                {% set link = path('team_submission', {submitId: submission.submitid}) %}
+                {% set link = path('team_submission', {submitId: submission.externalid}) %}
             {% endif %}
 
             {% set classes = '' %}
@@ -43,7 +43,7 @@
                 </td>
                 <td class="langid">
                     <a data-ajax-modal data-ajax-modal-after="markSeen" {% if link %}href="{{ link }}"{% endif %} title="{{ submission.language.name }}">
-                        {{ submission.language.langid }}
+                        {{ submission.language.name }}
                     </a>
                 </td>
                 <td>
@@ -78,7 +78,7 @@
         {% endif %}
         {% if allowDownload %}
                 <td>
-                    <a title="Download submission ZIP" aria-label="download submission zip" href="{{ path('team_submission_download', {'submitId': submission.submitid}) }}">
+                    <a title="Download submission ZIP" aria-label="download submission zip" href="{{ path('team_submission_download', {'submitId': submission.externalid}) }}">
                         <i class="fa fa-file-archive"></i>
                     </a>
                 </td>
diff --git a/webapp/templates/team/partials/submit_scripts.html.twig b/webapp/templates/team/partials/submit_scripts.html.twig
index bf0bdb1af6..08182ecdbe 100644
--- a/webapp/templates/team/partials/submit_scripts.html.twig
+++ b/webapp/templates/team/partials/submit_scripts.html.twig
@@ -4,7 +4,7 @@
         return filename.replace(/\.[^\.]*$/, '');
     }
 
-    function entryPointDetectKt(filename) {
+    function entryPointDetectKotlin(filename) {
         var filebase = filename.replace(/\.[^\.]*$/, '');
         if (filebase === '') return '_Kt';
 
@@ -44,8 +44,8 @@
                 case 'java':
                     $entryPointInput.val(entryPointDetectJava(filename));
                     break;
-                case 'kt':
-                    $entryPointInput.val(entryPointDetectKt(filename));
+                case 'kotlin':
+                    $entryPointInput.val(entryPointDetectKotlin(filename));
                     break;
                 default:
                     $entryPointInput.val(filename);
diff --git a/webapp/tests/Unit/Controller/API/BalloonsControllerTest.php b/webapp/tests/Unit/Controller/API/BalloonsControllerTest.php
index 62314bd84b..19d909c7ac 100644
--- a/webapp/tests/Unit/Controller/API/BalloonsControllerTest.php
+++ b/webapp/tests/Unit/Controller/API/BalloonsControllerTest.php
@@ -37,7 +37,7 @@ public function testBalloonsNoJudgings(): void
 
     public function testMarkAsDone(): void
     {
-        $expectedBalloon = ['team'=>'t2: Example teamname', 'problem'=>'U'];
+        $expectedBalloon = ['team'=>'exteam: Example teamname', 'problem'=>'U'];
         $contestId = $this->getUnitContestId();
         $url = "/contests/$contestId/balloons?todo=1";
         $this->loadFixtures([BalloonCorrectSubmissionFixture::class,BalloonUserFixture::class]);
diff --git a/webapp/tests/Unit/Controller/API/ConfigControllerTest.php b/webapp/tests/Unit/Controller/API/ConfigControllerTest.php
index d596ab58e2..b57ed5bae3 100644
--- a/webapp/tests/Unit/Controller/API/ConfigControllerTest.php
+++ b/webapp/tests/Unit/Controller/API/ConfigControllerTest.php
@@ -166,7 +166,7 @@ public function testConfigCheckerWorksForAdmin(): void
         // In the test setup, the config check returns some errors so expected result is 260.
         $response = $this->verifyApiJsonResponse('GET', $this->endpoint .'/check', 260, 'admin');
 
-        $sections = ['System', 'Configuration', 'Contests', 'Problems and languages', 'Teams', 'External identifiers'];
+        $sections = ['System', 'Configuration', 'Contests', 'Problems and languages', 'Teams', 'Identifiers'];
         static::assertIsArray($response);
         static::assertEquals($sections, array_keys($response));
 
diff --git a/webapp/tests/Unit/Controller/API/ScoreboardControllerTest.php b/webapp/tests/Unit/Controller/API/ScoreboardControllerTest.php
index c9841ca20b..033d64b43d 100644
--- a/webapp/tests/Unit/Controller/API/ScoreboardControllerTest.php
+++ b/webapp/tests/Unit/Controller/API/ScoreboardControllerTest.php
@@ -66,10 +66,10 @@ public function testFilteredScoreboard(array $filters, int $expectedCount): void
 
     public function provideFilters(): Generator
     {
-        yield [['category=3'], 1];
-        yield [['category=1', 'sortorder=9', 'allteams=true'], 1];
-        yield [['category=1', 'sortorder=9'], 0];
-        yield [['affiliation=1'], 1];
+        yield [['category=participants'], 1];
+        yield [['category=system', 'sortorder=9', 'allteams=true'], 1];
+        yield [['category=system', 'sortorder=9'], 0];
+        yield [['affiliation=utrecht'], 1];
         yield [['public=true'], 1]; // Scoreboard is frozen but has no results so those are the same
         yield [['public=false'], 1];
         yield [['sortorder=0'], 1];
@@ -82,6 +82,6 @@ public function provideFilters(): Generator
         yield [['country=NLD'], 1];
         yield [['country=AAA'], 0];
         yield [['country=USA'], 0];
-        yield [['category=2'], 0];
+        yield [['category=self-registered'], 0];
     }
 }
diff --git a/webapp/tests/Unit/Controller/API/SubmissionControllerTest.php b/webapp/tests/Unit/Controller/API/SubmissionControllerTest.php
index 1bfe4fba36..b8bdeafaa1 100644
--- a/webapp/tests/Unit/Controller/API/SubmissionControllerTest.php
+++ b/webapp/tests/Unit/Controller/API/SubmissionControllerTest.php
@@ -305,7 +305,7 @@ public function testAddSuccess(
         static::assertEquals($expectedProblemId, $submission->getProblem()->getProbid(), 'Wrong problem ID');
         static::assertEquals($expectedTeamId, $submission->getTeam()->getTeamid(), 'Wrong team ID');
         static::assertEquals($expectedUsername, $submission->getUser()->getUserIdentifier(), 'Wrong user');
-        static::assertEquals($expectedLanguageId, $submission->getLanguage()->getLangid(), 'Wrong language ID');
+        static::assertEquals($expectedLanguageId, $submission->getLanguage()->getExternalid(), 'Wrong language ID');
         if ($expectedSubmissionExternalId) {
             static::assertEquals($expectedSubmissionExternalId, $submission->getExternalid(), 'Wrong external submission ID');
         }
@@ -390,7 +390,7 @@ public function provideAddSuccess(): Generator
             1,
             2,
             'demo',
-            'kt',
+            'kotlin',
             null,
             null,
             ['somefile.kt' => file_get_contents(__FILE__)],
diff --git a/webapp/tests/Unit/Controller/Jury/ClarificationControllerTest.php b/webapp/tests/Unit/Controller/Jury/ClarificationControllerTest.php
index 69ba03609a..4fdf38caff 100644
--- a/webapp/tests/Unit/Controller/Jury/ClarificationControllerTest.php
+++ b/webapp/tests/Unit/Controller/Jury/ClarificationControllerTest.php
@@ -78,7 +78,7 @@ public function testClarificationRequestView(): void
                            trim($clarificationText[1]));
 
         $this->verifyLinkToURL('Example teamname',
-                               'http://localhost/jury/teams/2');
+                               'http://localhost/jury/teams/exteam');
     }
 
     /**
@@ -107,7 +107,7 @@ public function testClarificationRequestComposeForm(): void
 
         $this->client->submitForm('Send', [
             'jury_clarification[recipient]' => '',
-            'jury_clarification[subject]' => '1-tech',
+            'jury_clarification[subject]' => 'demo#tech',
             'jury_clarification[message]' => 'This is a clarification',
         ]);
 
diff --git a/webapp/tests/Unit/Controller/Jury/ContestControllerTest.php b/webapp/tests/Unit/Controller/Jury/ContestControllerTest.php
index b3ed5e127d..c777e99440 100644
--- a/webapp/tests/Unit/Controller/Jury/ContestControllerTest.php
+++ b/webapp/tests/Unit/Controller/Jury/ContestControllerTest.php
@@ -17,14 +17,14 @@ class ContestControllerTest extends JuryControllerTestCase
     protected static string  $shortTag                 = 'contest';
     protected static array   $deleteEntities           = ['Demo contest'];
     protected static string  $deleteEntityIdentifier   = 'name';
-    protected static string  $getIDFunc                = 'getCid';
+    protected static string  $getIDFunc                = 'getExternalid';
     protected static string  $className                = Contest::class;
     protected static array $DOM_elements               = ['h1'                            => ['Contests'],
                                                           'h3'                            => ['admin' => ['Current contests', 'All available contests'],
                                                              'jury' => []],
                                                           'a.btn[title="Import contest"]' => ['admin' => [" Import contest"],'jury'=>[]]];
-    protected static ?array $deleteExtra               = ['pageurl'   => '/jury/contests/1',
-                                                          'deleteurl' => '/jury/contests/1/problems/3/delete',
+    protected static ?array $deleteExtra               = ['pageurl'   => '/jury/contests/demo',
+                                                          'deleteurl' => '/jury/contests/demo/problems/boolfind/delete',
                                                           'selector'  => 'Boolean switch search',
                                                           'fixture'   => null];
     protected static string $addForm                   = 'contest[';
@@ -48,7 +48,7 @@ class ContestControllerTest extends JuryControllerTestCase
                                                            'goldMedals'               => '1',
                                                            'silverMedals'             => '1',
                                                            'bronzeMedals'             => '1',
-                                                           'medalCategories'          => ['0' => '2']],
+                                                           'medalCategories'          => ['0' => 'self-registered']],
                                                           ['shortname'            => 'CLICS_offset_HMM',
                                                            'name'                 => 'No Timezone but only offset',
                                                            'activatetimeString'   => '2021-07-17 16:08:00+1:11',
@@ -246,7 +246,7 @@ class ContestControllerTest extends JuryControllerTestCase
                                                            'silverMedals' => '0',
                                                            'bronzeMedals' => '0',
                                                            'medalsEnabled' => '1',
-                                                           'medalCategories' => ['0' => '2']],
+                                                           'medalCategories' => ['0' => 'self-registered']],
                                                           ['shortname' => 'prob',
                                                            'problems' => ['0' => ['shortname' => 'boolfind',
                                                                                   'points' => '1',
@@ -254,24 +254,24 @@ class ContestControllerTest extends JuryControllerTestCase
                                                                                   'allowJudge' => '1',
                                                                                   'color' => '#ffffff',
                                                                                   'lazyEvalResults' => '0',
-                                                                                  'problem' => '2']]],
+                                                                                  'problem' => 'fltcmp']]],
                                                           ['shortname' => 'multprob',
                                                            'name' => 'Contest with problems',
-                                                           'problems' => ['0' => ['problem' => '2',
+                                                           'problems' => ['0' => ['problem' => 'fltcmp',
                                                                                   'shortname' => 'fcmp',
                                                                                   'points' => '2',
                                                                                   'allowSubmit' => '1',
                                                                                   'allowJudge' => '1',
                                                                                   'color' => '#000000',
                                                                                   'lazyEvalResults' => '0'],
-                                                                          '1' => ['problem' => '1',
+                                                                          '1' => ['problem' => 'hello',
                                                                                   'shortname' => 'hw',
                                                                                   'points' => '1',
                                                                                   'allowSubmit' => '0',
                                                                                   'allowJudge' => '1',
                                                                                   'color' => '#000000',
                                                                                   'lazyEvalResults' => '0'],
-                                                                          '2' => ['problem' => '3',
+                                                                          '2' => ['problem' => 'boolfind',
                                                                                   'shortname' => 'p3',
                                                                                   'points' => '1',
                                                                                   'allowSubmit' => '1',
@@ -280,7 +280,7 @@ class ContestControllerTest extends JuryControllerTestCase
                                                                                   'lazyEvalResults' => '1']]],
                                                           ['shortname' => 'singleprobspecialchars',
                                                            'name' => 'Contest shortname with special chars',
-                                                           'problems' => ['0' => ['problem' => '2',
+                                                           'problems' => ['0' => ['problem' => 'fltcmp',
                                                                                   'shortname' => '!@#$%^&*()chars<>',
                                                                                   'points' => '2',
                                                                                   'allowSubmit' => '1',
@@ -342,7 +342,7 @@ public function testUnlockJudgeTasks(): void
 
         // Now, disable the problem.
         $contest = $em->getRepository(Contest::class)->findOneBy(['shortname' => 'demo']);
-        $contestId = $contest->getCid();
+        $contestId = $contest->getExternalid();
         $url = "/jury/contests/$contestId/edit";
         $this->verifyPageResponse('GET', $url, 200);
 
@@ -444,7 +444,7 @@ public function testLockedContest(): void
         $em = static::getContainer()->get(EntityManagerInterface::class);
         $contest = $em->getRepository(Contest::class)->findOneBy(['shortname' => 'demo']);
         $contest->setIsLocked(false);
-        $contestId = $contest->getCid();
+        $contestId = $contest->getExternalid();
         $editUrl = "/jury/contests/$contestId/edit";
         $deleteUrl = "/jury/contests/$contestId/delete";
         $contestUrl = "/jury/contests/$contestId";
diff --git a/webapp/tests/Unit/Controller/Jury/ImportExportControllerTest.php b/webapp/tests/Unit/Controller/Jury/ImportExportControllerTest.php
index 0083f5e9ab..8c4d8a2ff4 100644
--- a/webapp/tests/Unit/Controller/Jury/ImportExportControllerTest.php
+++ b/webapp/tests/Unit/Controller/Jury/ImportExportControllerTest.php
@@ -116,7 +116,7 @@ public function provideContestYamlContents(): Generator
         rgb: '#9B630C'
 
 HEREDOC;
-        yield ["1", $yaml];
+        yield ["demo", $yaml];
     }
 
     /**
diff --git a/webapp/tests/Unit/Controller/Jury/JuryMiscControllerTest.php b/webapp/tests/Unit/Controller/Jury/JuryMiscControllerTest.php
index bda8ae8583..66ecda2099 100644
--- a/webapp/tests/Unit/Controller/Jury/JuryMiscControllerTest.php
+++ b/webapp/tests/Unit/Controller/Jury/JuryMiscControllerTest.php
@@ -110,7 +110,7 @@ public function testBalloonScoreboard(array $fixtures, bool $public, string $con
                 }
             }
         }
-        foreach (range(1, 3) as $id) {
+        foreach (['hello', 'fltcmp', 'boolfind'] as $id) {
             $statusCode = in_array($contestStage, ['preActivation','preStart','postDeactivate']) || !$public ? 404 : 200;
             $this->verifyPageResponse('HEAD', '/public/problems/'.$id.'/statement', $statusCode);
         }
@@ -175,44 +175,44 @@ public function provideJuryAjax(): Generator
     {
         foreach ([200 => ['balloon','jury','admin'], 403 => ['team']] as $status => $roles) {
             foreach ($roles as $role) {
-                yield ['affiliations', $status, [$role], ['results' => [0 => ['id' => 1,
-                                                                              'text' => 'Utrecht University (1)']
+                yield ['affiliations', $status, [$role], ['results' => [0 => ['id' => 'utrecht',
+                                                                              'text' => 'Utrecht University (utrecht)']
                                                                        ]]];
                 yield ['locations', $status, [$role], ['results' => []]];
             }
         }
         foreach ([200 => ['jury','admin'], 403 => ['balloon','team']] as $status => $roles) {
             foreach ($roles as $role) {
-                yield ['problems', $status, [$role], ['results' => [0 => ['id' => 3, 'text' => 'Boolean switch search (p3)'],
-                                                                    1 => ['id' => 2,
-                                                                          'text' => 'Float special compare test (p2)'],
-                                                                    2 => ['id' => 1, 'text' => 'Hello World (p1)']]]];
-                yield ['teams', $status, [$role], ['results' => [0 => ['id' => 1, 'text' => 'DOMjudge (t1)'],
-                                                                 1 => ['id' => 2, 'text' => 'Example teamname (t2)']]]];
-                yield ['languages', $status, [$role], ['results' => [0 => ['id' => 'adb', 'text' => 'Ada (adb)'],
+                yield ['problems', $status, [$role], ['results' => [0 => ['id' => 'boolfind', 'text' => 'Boolean switch search (boolfind)'],
+                                                                    1 => ['id' => 'fltcmp',
+                                                                          'text' => 'Float special compare test (fltcmp)'],
+                                                                    2 => ['id' => 'hello', 'text' => 'Hello World (hello)']]]];
+                yield ['teams', $status, [$role], ['results' => [0 => ['id' => 'domjudge', 'text' => 'DOMjudge (domjudge)'],
+                                                                 1 => ['id' => 'exteam', 'text' => 'Example teamname (exteam)']]]];
+                yield ['languages', $status, [$role], ['results' => [0 => ['id' => 'ada', 'text' => 'Ada (ada)'],
                                                                      1 => ['id' => 'awk', 'text' => 'AWK (awk)'],
                                                                      2 => ['id' => 'bash', 'text' => 'Bash shell (bash)'],
                                                                      3 => ['id' => 'c', 'text' => 'C (c)'],
                                                                      4 => ['id' => 'csharp', 'text' => 'C# (csharp)'],
                                                                      5 => ['id' => 'cpp', 'text' => 'C++ (cpp)'],
                                                                      6 => ['id' => 'f95', 'text' => 'Fortran (f95)'],
-                                                                     7 => ['id' => 'hs', 'text' => 'Haskell (hs)'],
+                                                                     7 => ['id' => 'haskell', 'text' => 'Haskell (haskell)'],
                                                                      8 => ['id' => 'java', 'text' => 'Java (java)'],
-                                                                     9 => ['id' => 'js', 'text' => 'JavaScript (js)'],
-                                                                     10 => ['id' => 'kt', 'text' => 'Kotlin (kt)'],
+                                                                     9 => ['id' => 'javascript', 'text' => 'JavaScript (javascript)'],
+                                                                     10 => ['id' => 'kotlin', 'text' => 'Kotlin (kotlin)'],
                                                                      11 => ['id' => 'lua', 'text' => 'Lua (lua)'],
                                                                      12 => ['id' => 'ocaml', 'text' => 'OCaml (ocaml)'],
-                                                                     13 => ['id' => 'pas', 'text' => 'Pascal (pas)'],
+                                                                     13 => ['id' => 'pascal', 'text' => 'Pascal (pascal)'],
                                                                      14 => ['id' => 'pl', 'text' => 'Perl (pl)'],
                                                                      15 => ['id' => 'sh', 'text' => 'POSIX shell (sh)'],
-                                                                     16 => ['id' => 'plg', 'text' => 'Prolog (plg)'],
-                                                                     17 => ['id' => 'py3', 'text' => 'Python 3 (py3)'],
+                                                                     16 => ['id' => 'prolog', 'text' => 'Prolog (prolog)'],
+                                                                     17 => ['id' => 'python3', 'text' => 'Python 3 (python3)'],
                                                                      18 => ['id' => 'r', 'text' => 'R (r)'],
-                                                                     19 => ['id' => 'rb', 'text' => 'Ruby (rb)'],
-                                                                     20 => ['id' => 'rs', 'text' => 'Rust (rs)'],
+                                                                     19 => ['id' => 'ruby', 'text' => 'Ruby (ruby)'],
+                                                                     20 => ['id' => 'rust', 'text' => 'Rust (rust)'],
                                                                      21 => ['id' => 'scala', 'text' => 'Scala (scala)'],
                                                                      22 => ['id' => 'swift', 'text' => 'Swift (swift)']]]];
-                yield ['contests', $status, [$role], ['results' => [0 => ['id' => 1, 'text' => 'Demo contest (demo - c1)']
+                yield ['contests', $status, [$role], ['results' => [0 => ['id' => 'demo', 'text' => 'Demo contest (demo - demo)']
                                                                    ]]];
             }
         }
diff --git a/webapp/tests/Unit/Controller/Jury/LanguagesControllerTest.php b/webapp/tests/Unit/Controller/Jury/LanguagesControllerTest.php
index 467a90f44f..b8fb40936f 100644
--- a/webapp/tests/Unit/Controller/Jury/LanguagesControllerTest.php
+++ b/webapp/tests/Unit/Controller/Jury/LanguagesControllerTest.php
@@ -17,14 +17,13 @@ class LanguagesControllerTest extends JuryControllerTestCase
     protected static string  $shortTag                 = 'language';
     protected static array   $deleteEntities           = ['C++','C#','C','Kotlin'];
     protected static string  $deleteEntityIdentifier   = 'name';
-    protected static string  $getIDFunc                = 'getLangid';
+    protected static string  $getIDFunc                = 'getExternalid';
     protected static string  $className                = Language::class;
     protected static array   $DOM_elements             = ['h1' => ['Enabled languages', 'Disabled languages']];
     protected static ?string $addPlus                  = 'extensions';
     protected static string  $addForm                  = 'language[';
-    protected static array   $addEntitiesShown         = ['langid', 'externalid', 'name', 'timefactor'];
-    protected static array   $addEntities              = [['langid' => 'simple',
-                                                           'name' => 'Simple',
+    protected static array   $addEntitiesShown         = ['externalid', 'name', 'timefactor'];
+    protected static array   $addEntities              = [['name' => 'Simple',
                                                            'externalid' => 'extSimple',
                                                            'requireEntryPoint' => '0',
                                                            'entryPointDescription' => '',
@@ -34,53 +33,33 @@ class LanguagesControllerTest extends JuryControllerTestCase
                                                            'compileExecutable' => 'java_javac',
                                                            'extensions' => ['1' => 'extension'],
                                                            'filterCompilerFiles' => '1'],
-                                                          ['langid' => 'ext',
-                                                           'externalid' => 'diffext',
+                                                          ['externalid' => 'diffext',
                                                            'name' => 'External'],
-                                                          ['langid' => 'lang123_.-',
-                                                           'name' => 'langid_expected_chars'],
-                                                          ['langid' => 'external_expected_chars',
-                                                           'externalid' => 'ext123_.-'],
-                                                          ['langid' => 'name_special_chars',
-                                                           'name' => '🕑ড|{}()*'],
-                                                          ['langid' => 'entry',
-                                                           'requireEntryPoint' => '1',
+                                                          ['name' => 'langid_expected_chars'],
+                                                          ['externalid' => 'ext123_.-'],
+                                                          ['name' => '🕑ড|{}()*'],
+                                                          ['requireEntryPoint' => '1',
                                                            'entryPointDescription' => 'shell'],
-                                                          ['langid' => 'entry_nodesc',
-                                                           'requireEntryPoint' => '1',
+                                                          ['requireEntryPoint' => '1',
                                                            'entryPointDescription' => ''],
-                                                          ['langid' => 'nosub',
-                                                           'allowSubmit' => '0'],
-                                                          ['langid' => 'nojud',
-                                                           'allowJudge' => '0'],
-                                                          ['langid' => 'timef1',
-                                                           'timeFactor' => '3'],
-                                                          ['langid' => 'timef2',
-                                                           'timeFactor' => '1.3'],
-                                                          ['langid' => 'timef3',
-                                                           'timeFactor' => '0.5'],
-                                                          ['langid' => 'comp',
-                                                           'compileExecutable' => 'swift'],
-                                                          ['langid' => 'multex',
-                                                           'extensions' => ['0' => 'a', '1' => 'b',
+                                                          ['allowSubmit' => '0'],
+                                                          ['allowJudge' => '0'],
+                                                          ['timeFactor' => '3'],
+                                                          ['timeFactor' => '1.3'],
+                                                          ['timeFactor' => '0.5'],
+                                                          ['compileExecutable' => 'swift'],
+                                                          ['extensions' => ['0' => 'a', '1' => 'b',
                                                                             '2' => '1', '3' => ',']],
-                                                          ['langid' => 'extunicode',
-                                                           'extensions' => ['0' => '🕑']],
-                                                          ['langid' => 'nofilt',
-                                                           'filterCompilerFiles' => '0'],
-                                                          ['langid' => 'compVers',
-                                                           'compilerVersionCommand' => 'unit -V'],
-                                                          ['langid' => 'runVers',
-                                                           'runnerVersionCommand' => 'run -x |yes|tr "\n" "\`true\`"']];
-    protected static array   $addEntitiesFailure       = ['Only alphanumeric characters and ._- are allowed' => [['langid' => '§$#`"'],
-                                                                                                                 ['langid' => '()*&']],
-                                                          'Only letters, numbers, dashes, underscores and dots are allowed.' => [['externalid' => '§$#'],
+                                                          ['extensions' => ['0' => '🕑']],
+                                                          ['filterCompilerFiles' => '0'],
+                                                          ['compilerVersionCommand' => 'unit -V'],
+                                                          ['runnerVersionCommand' => 'run -x |yes|tr "\n" "\`true\`"']];
+    protected static array   $addEntitiesFailure       = ['Only letters, numbers, dashes, underscores and dots are allowed.' => [['externalid' => '§$#'],
                                                                                                                                 ['externalid' => '@#()|']],
                                                           'This value should be positive.' => [['timeFactor' => '0'],
                                                                                                ['timeFactor' => '-1'],
                                                                                                ['timeFactor' => '-.1']],
-                                                          'This value should not be blank.' => [['langid' => ''],
-                                                                                                ['name' => '']]];
+                                                          'This value should not be blank.' => [['name' => '']]];
 
     public function helperProvideTranslateAddEntity(array $entity, array $expected): array
     {
diff --git a/webapp/tests/Unit/Controller/Jury/ProblemControllerTest.php b/webapp/tests/Unit/Controller/Jury/ProblemControllerTest.php
index 410dc4f859..6ddd3587bc 100644
--- a/webapp/tests/Unit/Controller/Jury/ProblemControllerTest.php
+++ b/webapp/tests/Unit/Controller/Jury/ProblemControllerTest.php
@@ -13,11 +13,11 @@
 class ProblemControllerTest extends JuryControllerTestCase
 {
     protected static string  $baseUrl                  = '/jury/problems';
-    protected static array   $exampleEntries           = ['Hello World', 'default', 5, 3, 2, 1];
+    protected static array   $exampleEntries           = ['Hello World', 'default', 5, 'boolfind', 'fltcmp', 'hello'];
     protected static string  $shortTag                 = 'problem';
     protected static array   $deleteEntities           = ['Hello World','Float special compare test'];
     protected static string  $deleteEntityIdentifier   = 'name';
-    protected static string  $getIDFunc                = 'getProbid';
+    protected static string  $getIDFunc                = 'getExternalid';
     protected static string  $className                = Problem::class;
     protected static array   $DOM_elements             = [
         'h1'                            => ['Problems in contest Demo contest'],
@@ -28,7 +28,7 @@ class ProblemControllerTest extends JuryControllerTestCase
     // Note: we replace the deleteurl in testDeleteExtraEntity below with the actual attachment ID.
     // This can change when running the tests multiple times.
     protected static ?array $deleteExtra      = [
-        'pageurl'   => '/jury/problems/3',
+        'pageurl'   => '/jury/problems/boolfind',
         'deleteurl' => '/jury/problems/attachments/1/delete',
         'selector'  => 'interactor'
     ];
@@ -89,7 +89,7 @@ public function testLockedContest(): void
         $contest->setIsLocked(true);
         $contestId = $contest->getCid();
         $problem = $em->getRepository(Problem::class)->findOneBy(['probid' => 1]);
-        $probId = $problem->getProbid();
+        $probId = $problem->getExternalid();
         $editUrl = "/jury/problems/$probId/edit";
         $deleteUrl = "/jury/problems/$probId/delete";
         $problemUrl = "/jury/problems/$probId";
@@ -158,7 +158,7 @@ public function testMultiDeleteProblems(): void
 
         // Get the IDs of the newly created problems
         foreach ($createdProblems as $problem) {
-            $problemIds[] = $problem->getProbid();
+            $problemIds[] = $problem->getExternalid();
         }
 
         $problem1Id = $problemIds[0];
diff --git a/webapp/tests/Unit/Controller/Jury/TeamAffiliationControllerTest.php b/webapp/tests/Unit/Controller/Jury/TeamAffiliationControllerTest.php
index 0db62b576c..4be9be6a98 100644
--- a/webapp/tests/Unit/Controller/Jury/TeamAffiliationControllerTest.php
+++ b/webapp/tests/Unit/Controller/Jury/TeamAffiliationControllerTest.php
@@ -15,7 +15,7 @@ class TeamAffiliationControllerTest extends JuryControllerTestCase
     protected static array   $deleteEntities           = ['UU','FAU'];
     protected static string  $deleteEntityIdentifier   = 'shortname';
     protected static array   $deleteFixtures           = [SampleAffiliationsFixture::class];
-    protected static string  $getIDFunc                = 'getAffilid';
+    protected static string  $getIDFunc                = 'getExternalid';
     protected static string  $className                = TeamAffiliation::class;
     protected static array   $DOM_elements             = ['h1' => ['Affiliations']];
     protected static string  $identifyingEditAttribute = 'shortname';
@@ -82,7 +82,7 @@ public function testMultiDeleteTeamAffiliations(): void
 
         // Get the IDs of the newly created affiliations
         foreach ($createdAffiliations as $affiliation) {
-            $affiliationIds[] = $affiliation->getAffilid();
+            $affiliationIds[] = $affiliation->getExternalid();
         }
 
         $affiliation1Id = $affiliationIds[0];
diff --git a/webapp/tests/Unit/Controller/Jury/TeamCategoryControllerTest.php b/webapp/tests/Unit/Controller/Jury/TeamCategoryControllerTest.php
index 95ba0ce4a4..09e6495d8e 100644
--- a/webapp/tests/Unit/Controller/Jury/TeamCategoryControllerTest.php
+++ b/webapp/tests/Unit/Controller/Jury/TeamCategoryControllerTest.php
@@ -14,7 +14,7 @@ class TeamCategoryControllerTest extends JuryControllerTestCase
     protected static string  $shortTag                 = 'category';
     protected static array   $deleteEntities           = ['System','Observers'];
     protected static string  $deleteEntityIdentifier   = 'name';
-    protected static string  $getIDFunc                = 'getCategoryid';
+    protected static string  $getIDFunc                = 'getExternalid';
     protected static string  $className                = TeamCategory::class;
     protected static array   $DOM_elements             = ['h1' => ['Categories']];
     protected static string  $addForm                  = 'team_category[';
@@ -86,7 +86,7 @@ public function testMultiDeleteTeamCategories(): void
 
         // Get the IDs of the newly created categories
         foreach ($createdCategories as $category) {
-            $categoryIds[] = $category->getCategoryid();
+            $categoryIds[] = $category->getExternalid();
         }
 
         $category1Id = $categoryIds[0];
diff --git a/webapp/tests/Unit/Controller/Jury/TeamControllerTest.php b/webapp/tests/Unit/Controller/Jury/TeamControllerTest.php
index 54d6ec5696..a0b5f6191f 100644
--- a/webapp/tests/Unit/Controller/Jury/TeamControllerTest.php
+++ b/webapp/tests/Unit/Controller/Jury/TeamControllerTest.php
@@ -16,17 +16,17 @@ class TeamControllerTest extends JuryControllerTestCase
     protected static string  $shortTag                 = 'team';
     protected static array   $deleteEntities           = ['DOMjudge','Example teamname'];
     protected static string  $deleteEntityIdentifier   = 'name';
-    protected static string  $getIDFunc                = 'getTeamid';
+    protected static string  $getIDFunc                = 'getExternalid';
     protected static string  $className                = Team::class;
     protected static array   $DOM_elements             = ['h1' => ['Teams']];
     protected static string  $addForm                  = 'team[';
     protected static array   $addEntitiesShown         = ['icpcid', 'label', 'displayName', 'location'];
-    protected static array   $overviewSingleNotShown   = ['addUserForTeam'];
+    protected static array   $overviewSingleNotShown   = ['addUserForTeam', 'category'];
     protected static array   $overviewGeneralNotShown  = ['icpcid'];
     protected static array   $addEntitiesCount         = ['contests'];
     protected static array   $addEntities              = [['name' => 'New Team',
                                                            'displayName' => 'New Team Display Name',
-                                                           'category' => '3',
+                                                           'category' => 'participants',
                                                            'publicdescription' => 'Some members',
                                                            'penalty' => '0',
                                                            'location' => 'The first room',
@@ -37,7 +37,7 @@ class TeamControllerTest extends JuryControllerTestCase
                                                            'icpcid' => ''],
                                                           ['name' => 'Another Team',
                                                            'displayName' => 'Another Team Display Name',
-                                                           'category' => '1',
+                                                           'category' => 'system',
                                                            'publicdescription' => 'More members',
                                                            'penalty' => '20',
                                                            'location' => 'Another room',
@@ -47,12 +47,12 @@ class TeamControllerTest extends JuryControllerTestCase
                                                            'newUsername' => 'linkeduser'],
                                                           ['name' => 'Team linked to existing user',
                                                            'displayName' => 'Third team display name',
-                                                           'category' => '1',
+                                                           'category' => 'system',
                                                            'publicdescription' => 'Members of this team',
                                                            'penalty' => '0',
                                                            'enabled' => '1',
                                                            'addUserForTeam' => Team::ADD_EXISTING_USER,
-                                                           'existingUser' => 3],
+                                                           'existingUser' => 'demo'],
                                                           ['name' => 'external_ID',
                                                            'label' => 'teamlabel',
                                                            'displayName' => 'With External ID'],
@@ -124,7 +124,7 @@ public function testMultiDeleteTeams(): void
 
         // Get the IDs of the newly created teams
         foreach ($createdTeams as $team) {
-            $teamIds[] = $team->getTeamid();
+            $teamIds[] = $team->getExternalid();
         }
 
         $team1Id = $teamIds[0];
diff --git a/webapp/tests/Unit/Controller/Jury/UserControllerTest.php b/webapp/tests/Unit/Controller/Jury/UserControllerTest.php
index 1843de2e25..862023d288 100644
--- a/webapp/tests/Unit/Controller/Jury/UserControllerTest.php
+++ b/webapp/tests/Unit/Controller/Jury/UserControllerTest.php
@@ -16,7 +16,7 @@ class UserControllerTest extends JuryControllerTestCase
     protected static string  $shortTag                 = 'user';
     protected static array   $deleteEntities           = ['demo','judgehost'];
     protected static string  $deleteEntityIdentifier   = 'username';
-    protected static string  $getIDFunc                = 'getUserid';
+    protected static string  $getIDFunc                = 'getExternalid';
     protected static string  $className                = User::class;
     protected static array   $DOM_elements             = ['h1' => ['Users']];
     protected static string  $addForm                  = 'user[';
@@ -28,7 +28,7 @@ class UserControllerTest extends JuryControllerTestCase
                                                            'plainPassword' => 'plainpassword',
                                                            'ipAddress'     => '10.0.0.0',
                                                            'enabled'       => '1',
-                                                           'team'          => '0',
+                                                           'team'          => '',
                                                            'user_roles'    => ['0' => true, '1' => true]],
                                                           ['username' => 'ABCabc123_-@', 'name' => 'Allowed username'],
                                                           ['username' => 'nem', 'name' => 'No Email',
@@ -124,7 +124,7 @@ public function testMultiDeleteUsers(): void
 
         // Get the IDs of the newly created users
         foreach ($createdUsers as $user) {
-            $userIds[] = $user->getUserid();
+            $userIds[] = $user->getExternalid();
         }
 
         $user1Id = $userIds[0];
diff --git a/webapp/tests/Unit/Controller/Team/ClarificationControllerTest.php b/webapp/tests/Unit/Controller/Team/ClarificationControllerTest.php
index 31a31bb9c0..2ee13710ce 100644
--- a/webapp/tests/Unit/Controller/Team/ClarificationControllerTest.php
+++ b/webapp/tests/Unit/Controller/Team/ClarificationControllerTest.php
@@ -16,7 +16,7 @@ public function testClarificationRequest(): void
         $this->client->click($link);
 
         $this->client->submitForm('Send', [
-            'team_clarification[subject]' => '1-3',
+            'team_clarification[subject]' => 'demo|boolfind',
             'team_clarification[message]' => "I don't understand this problem",
         ]);
 
diff --git a/webapp/tests/Unit/Controller/Team/MiscControllerTest.php b/webapp/tests/Unit/Controller/Team/MiscControllerTest.php
index e76b3c6204..ace538518c 100644
--- a/webapp/tests/Unit/Controller/Team/MiscControllerTest.php
+++ b/webapp/tests/Unit/Controller/Team/MiscControllerTest.php
@@ -103,14 +103,14 @@ function () {
 
                 $crawler = $this->client->submitForm('Print code', [
                     'print[code]' => $code,
-                    'print[langid]' => 'kt',
+                    'print[langid]' => 'kotlin',
                 ]);
 
                 static::assertSelectorTextContains('div.alert.alert-success',
                     'File has been printed');
 
                 $text = trim($crawler->filter('pre')->text(null, false));
-                static::assertStringStartsWith('kt', $text);
+                static::assertStringStartsWith('kotlin', $text);
                 static::assertStringEndsWith(
                     trim(file_get_contents($testFile)), $text);
             });
diff --git a/webapp/tests/Unit/Controller/Team/ProblemControllerTest.php b/webapp/tests/Unit/Controller/Team/ProblemControllerTest.php
index 941169fdbe..ac758971ff 100644
--- a/webapp/tests/Unit/Controller/Team/ProblemControllerTest.php
+++ b/webapp/tests/Unit/Controller/Team/ProblemControllerTest.php
@@ -135,8 +135,8 @@ public function testSamples(): void
         // Check the link to download all samples.
         $link = $cardBodies->eq(1)->filter('a')->eq(2);
         self::assertSame('samples', $link->text(null, true));
-        self::assertSame(sprintf('/team/%d/samples.zip',
-            $problem->getProbid()),
+        self::assertSame(sprintf('/team/%s/samples.zip',
+            $problem->getExternalid()),
             $link->attr('href'));
 
         // Download the sample and make sure the contents are correct.
diff --git a/webapp/tests/Unit/Integration/ScoreboardIntegrationTest.php b/webapp/tests/Unit/Integration/ScoreboardIntegrationTest.php
index 8ff63433d4..e76341dda9 100644
--- a/webapp/tests/Unit/Integration/ScoreboardIntegrationTest.php
+++ b/webapp/tests/Unit/Integration/ScoreboardIntegrationTest.php
@@ -288,7 +288,7 @@ public function testTeamScoreboardFreezeFTS(): void
 
         $team = $this->teams[1];
 
-        $scoreboard = $this->ss->getTeamScoreboard($this->contest, $team->getTeamid(), false);
+        $scoreboard = $this->ss->getTeamScoreboard($this->contest, $team->getExternalid(), false);
 
         static::assertInstanceOf(SingleTeamScoreboard::class, $scoreboard);
         static::assertFTSMatch($expected_fts, $scoreboard);
@@ -296,7 +296,7 @@ public function testTeamScoreboardFreezeFTS(): void
 
     public function testOneSingleFTS(): void
     {
-        $lang = $this->em->getRepository(Language::class)->find('c');
+        $lang = $this->em->getRepository(Language::class)->findByExternalId('c');
 
         $team = $this->teams[0];
         $this->createSubmission($lang, $this->problems[0], $team, 53*60+15.053, 'correct', true)
@@ -329,7 +329,7 @@ public function testOneSingleFTS(): void
 
     public function testFTSwithVerificationRequired(): void
     {
-        $lang = $this->em->getRepository(Language::class)->find('c');
+        $lang = $this->em->getRepository(Language::class)->findByExternalId('c');
 
         $team = $this->teams[0];
         $this->createSubmission($lang, $this->problems[0], $team, 53*60+15.053, 'correct', true)
@@ -365,7 +365,7 @@ public function testFTSwithVerificationRequired(): void
 
     public function testFTSwithQueuedRejudging(): void
     {
-        $lang = $this->em->getRepository(Language::class)->find('c');
+        $lang = $this->em->getRepository(Language::class)->findByExternalId('c');
 
         $team = $this->teams[0];
         $this->createSubmission($lang, $this->problems[0], $team, 53 * 60 + 15.053, 'wrong-answer')
@@ -445,7 +445,7 @@ protected function recalcScoreCaches(): void
 
     protected function createDefaultSubmissions(): void
     {
-        $lang = $this->em->getRepository(Language::class)->find('cpp');
+        $lang = $this->em->getRepository(Language::class)->findByExternalId('cpp');
 
         $team = $this->teams[0];
         $this->createSubmission($lang, $this->problems[0], $team, 53*60+15.053, 'no-output');
diff --git a/webapp/tests/Unit/Service/ImportExportServiceTest.php b/webapp/tests/Unit/Service/ImportExportServiceTest.php
index 01453533af..1ce4b5beee 100644
--- a/webapp/tests/Unit/Service/ImportExportServiceTest.php
+++ b/webapp/tests/Unit/Service/ImportExportServiceTest.php
@@ -1302,7 +1302,7 @@ public function testGetResultsData(bool $full, bool $honors, string $dataSet, st
             $contestProblemsById[$contestProblem->getExternalid()] = $contestProblem;
         }
 
-        $cpp = $em->getRepository(Language::class)->find('cpp');
+        $cpp = $em->getRepository(Language::class)->findByExternalId('cpp');
 
         // We use direct queries here to speed this up
         $submissionInsertQuery = $em->getConnection()->prepare('INSERT INTO submission (teamid, cid, probid, langid, submittime) VALUES (:teamid, :cid, :probid, :langid, :submittime)');
@@ -1357,7 +1357,7 @@ public function testGetResultsData(bool $full, bool $honors, string $dataSet, st
         /** @var RequestStack $requestStack */
         $requestStack = static::getContainer()->get(RequestStack::class);
         $request = new Request();
-        $request->cookies->set('domjudge_cid', (string)$contest->getCid());
+        $request->cookies->set('domjudge_cid', (string)$contest->getExternalid());
         $requestStack->push($request);
 
         $results = $importExportService->getResultsData(37, $full, $honors);
diff --git a/webapp/var/log/.gitkeep b/webapp/var/log/.gitkeep
old mode 100755
new mode 100644