diff --git a/build.gradle.kts b/build.gradle.kts
index 643c40c2..27c11b5f 100644
--- a/build.gradle.kts
+++ b/build.gradle.kts
@@ -1,7 +1,7 @@
 plugins {
     java
-    id("com.gradleup.shadow") version("8.3.5")
-    id("com.github.ben-manes.versions") version("0.51.0")
+    id("com.gradleup.shadow") version("8.3.8")
+    id("com.github.ben-manes.versions") version("0.52.0")
 }
 
 // Change to true when releasing
@@ -14,17 +14,17 @@ version = "$majorVersion-$minorVersion"
 
 repositories {
     mavenCentral()
-    maven("https://s01.oss.sonatype.org/content/repositories/snapshots/")
+    maven("https://repo.papermc.io/repository/maven-public/")
     maven("https://repo.extendedclip.com/content/repositories/placeholderapi/")
-    maven("https://repo.glaremasters.me/repository/public/")
     maven("https://nexus.phoenixdevt.fr/repository/maven-public/")
     maven("https://repo.nexomc.com/releases/")
     maven("https://repo.oraxen.com/releases")
+    maven("https://maven.devs.beer/")
     maven("https://jitpack.io")
 }
 
 dependencies {
-    compileOnly(libs.spigot)
+    compileOnly(libs.paper)
 
     compileOnly(libs.vault)
     compileOnly(libs.authlib)
@@ -56,14 +56,15 @@ tasks {
         relocate("org.bstats", "com.extendedclip.deluxemenus.libs.bstats")
         archiveFileName.set("DeluxeMenus-${rootProject.version}.jar")
     }
+
     java {
-        sourceCompatibility = JavaVersion.VERSION_11
-        targetCompatibility = JavaVersion.VERSION_11
+        sourceCompatibility = JavaVersion.VERSION_21
+        targetCompatibility = JavaVersion.VERSION_21
         disableAutoTargetJvm()
     }
 
     processResources {
-        filesMatching("plugin.yml") {
+        filesMatching(listOf("plugin.yml", "paper-plugin.yml")) {
             expand("version" to rootProject.version)
         }
     }
diff --git a/gradle/libs.versions.toml b/gradle/libs.versions.toml
index 4f479961..9fadf790 100644
--- a/gradle/libs.versions.toml
+++ b/gradle/libs.versions.toml
@@ -1,14 +1,16 @@
 [versions]
 # Compile only
 spigot = "1.21.5-R0.1-SNAPSHOT"
+#paper = "1.17.1-R0.1-SNAPSHOT"
+paper = "1.21.7-R0.1-SNAPSHOT"
 vault = "1.7.1"
 authlib = "1.5.25"
 headdb = "1.3.2"
-itemsadder = "3.6.3-beta-14"
-nexo = "1.1.0"
+itemsadder = "4.0.10"
+nexo = "1.8.0"
 oraxen = "1.190.0"
 mythiclib = "1.7.1-SNAPSHOT"
-mmoitems = "6.10-SNAPSHOT"
+mmoitems = "6.10.1-SNAPSHOT"
 papi = "2.11.6"
 score = "4.24.3.5"
 sig = "1.5.0"
@@ -21,11 +23,11 @@ adventure-minimessage = "4.21.0"
 
 [libraries]
 # Compile only
-spigot = { module = "org.spigotmc:spigot-api", version.ref = "spigot" }
+paper = { module = "io.papermc.paper:paper-api", version.ref = "paper" }
 vault = { module = "com.github.milkbowl:VaultAPI", version.ref = "vault" }
 authlib = { module = "com.mojang:authlib", version.ref = "authlib" }
 headdb = { module = "com.arcaniax:HeadDatabase-API", version.ref = "headdb" }
-itemsadder = { module = "com.github.LoneDev6:api-itemsadder", version.ref = "itemsadder" }
+itemsadder = { module = "dev.lone:api-itemsadder", version.ref = "itemsadder" }
 nexo = { module = "com.nexomc:nexo", version.ref = "nexo" }
 oraxen = { module = "io.th0rgal:oraxen", version.ref = "oraxen" }
 mythiclib = { module = "io.lumine:MythicLib-dist", version.ref = "mythiclib"}
diff --git a/src/main/java/com/extendedclip/deluxemenus/menu/command/RegistrableMenuCommand.java b/src/main/java/com/extendedclip/deluxemenus/menu/command/RegistrableMenuCommand.java
index 3edf522b..6e315be0 100644
--- a/src/main/java/com/extendedclip/deluxemenus/menu/command/RegistrableMenuCommand.java
+++ b/src/main/java/com/extendedclip/deluxemenus/menu/command/RegistrableMenuCommand.java
@@ -32,7 +32,7 @@ public class RegistrableMenuCommand extends Command {
 
     public RegistrableMenuCommand(final @NotNull DeluxeMenus plugin,
                                   final @NotNull Menu menu) {
-        super(menu.options().commands().isEmpty() ? menu.options().name() : menu.options().commands().get(0));
+        super(menu.options().commands().isEmpty() ? menu.options().name() : menu.options().commands().getFirst());
         this.plugin = plugin;
         this.menu = menu;
 
@@ -42,12 +42,12 @@ public RegistrableMenuCommand(final @NotNull DeluxeMenus plugin,
     }
 
     @Override
-    public boolean execute(final @NotNull CommandSender sender, final @NotNull String commandLabel, final @NotNull String[] typedArgs) {
+    public boolean execute(final @NotNull CommandSender sender, final @NotNull String commandLabel, final @NotNull String @NotNull [] typedArgs) {
         if (this.unregistered) {
             throw new IllegalStateException("This command was unregistered!");
         }
 
-        if (!(sender instanceof Player)) {
+        if (!(sender instanceof Player player)) {
             Msg.msg(sender, "Menus can only be opened by players!");
             return true;
         }
@@ -77,7 +77,6 @@ public boolean execute(final @NotNull CommandSender sender, final @NotNull Strin
             }
         }
 
-        Player player = (Player) sender;
         plugin.debug(DebugLevel.LOWEST, Level.INFO, "opening menu: " + menu.options().name());
         menu.openMenu(player, argMap, null);
         return true;
@@ -138,6 +137,7 @@ public void unregister() {
             knownCommands = SimpleCommandMap.class.getDeclaredField("knownCommands");
             knownCommands.setAccessible(true);
 
+            //noinspection unchecked
             final Map<String, Command> knownCommandsMap = (Map<String, Command>) knownCommands.get(cMap.get(Bukkit.getServer()));
 
             // We need to remove every single alias because CommandMap#register() adds them all to the map.
diff --git a/src/main/java/com/extendedclip/deluxemenus/persistentmeta/PersistentMetaHandler.java b/src/main/java/com/extendedclip/deluxemenus/persistentmeta/PersistentMetaHandler.java
index bab7d857..11182d55 100644
--- a/src/main/java/com/extendedclip/deluxemenus/persistentmeta/PersistentMetaHandler.java
+++ b/src/main/java/com/extendedclip/deluxemenus/persistentmeta/PersistentMetaHandler.java
@@ -145,6 +145,7 @@ public <T> Map<String, T> getMetaValues(
             return OperationResult.NEW_VALUE_IS_DIFFERENT_TYPE;
         }
 
+        // TODO: Blitz: It seems that PersistentDataContainer#has(NamespacedKey) does not exist in 1.17.1.
         if (player.getPersistentDataContainer().has(key) &&
                 (!player.getPersistentDataContainer().has(key, type.getPDType()) || !type.isSupported(player.getPersistentDataContainer().get(key, type.getPDType())))) {
             return OperationResult.EXISTENT_VALUE_IS_DIFFERENT_TYPE;
diff --git a/src/main/java/com/extendedclip/deluxemenus/utils/ItemUtils.java b/src/main/java/com/extendedclip/deluxemenus/utils/ItemUtils.java
index 870e8312..7345d2c5 100644
--- a/src/main/java/com/extendedclip/deluxemenus/utils/ItemUtils.java
+++ b/src/main/java/com/extendedclip/deluxemenus/utils/ItemUtils.java
@@ -105,7 +105,7 @@ public static boolean hasPotionMeta(@NotNull final ItemStack itemStack) {
         final PotionMeta itemMeta = (PotionMeta) itemStack.getItemMeta();
 
         if (itemMeta != null) {
-            itemMeta.setBasePotionType(PotionType.WATER);
+            itemMeta.setBasePotionType(PotionType.WATER); // TODO: Blitz: Check if this works in 1.17.1 (seems that the setBasePotionType method was only added later)
             itemStack.setItemMeta(itemMeta);
         }
 
diff --git a/src/main/resources/paper-plugin.yml b/src/main/resources/paper-plugin.yml
new file mode 100644
index 00000000..0dd00eba
--- /dev/null
+++ b/src/main/resources/paper-plugin.yml
@@ -0,0 +1,5 @@
+name: DeluxeMenus
+version: '${version}'
+main: com.extendedclip.deluxemenus.DeluxeMenus
+description: All in one inventory menu system
+api-version: '1.13'
\ No newline at end of file