[Bug] Emoji triggers PDF-export crash and restarts container (CodiMD 2.6.0)

[AriesyuGTH]

Describe the bug

Exporting a note to PDF in CodiMD 2.6.0 crashes PhantomJS whenever the note contains certain emoji characters, which restarts the whole container.

To Reproduce

1. Create or edit a note.
2. Insert any emoji (e.g. 😀).
3. Click Export → PDF.
4. The request hangs and the container restarts.

Expected behavior

• A PDF should be generated successfully.
• The service should remain online.

Actual behavior

• PDF generation fails.
• docker logs show PhantomJS crashing with SIGFPE.
• The CodiMD container restarts automatically.

Environment

Item	Value
CodiMD ver.	2.6.0
Deployment	docker-compose
Node ver.	16.20.2 (image default)
Base OS	Debian Buster
PDF engine	markdown-pdf + PhantomJS

docker-compose excerpt (masked)

click to expand

services:
  codimd:
    image: <PRIVATE_REGISTRY>/hackmdio/hackmd:2.6.0
    environment:
      CMD_URL_PATH: codimd
      CMD_DOMAIN: <YOUR_DOMAIN>
      CMD_PROTOCOL_USESSL: "true"
      QT_QPA_PLATFORM: ""
      # Database
      CMD_DB_URL: postgres://codimd:<MASKED_PW>@codimd_db/codimd
      # Misc
      CMD_EMAIL: "false"
      CMD_PLANTUML_SERVER: https://<YOUR_DOMAIN>/plantuml
      CMD_ALLOW_ANONYMOUS: "false"
      CMD_ALLOW_ANONYMOUS_EDITS: "false"
      CMD_CSP_ENABLE: "false"

Logs (full excerpt)

2025-07-09T06:13:04.445Z info:  <MASKED_IP> - - [09/Jul/2025:06:13:04 +0000] "GET /me HTTP/1.1" 304 - "https://<YOUR_DOMAIN>/codimd/ixLMZtInSNiOnrbOkQ-Q_w" "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/138.0.0.0 Safari/537.36 Edg/138.0.0.0"
2025-07-09T06:13:06.517Z info:  <MASKED_IP> - - [09/Jul/2025:06:13:06 +0000] "GET /uploads/upload_845dbee74d2337302b91fb126a4691db.png HTTP/1.1" 200 32405 "https://<YOUR_DOMAIN>/codimd/ixLMZtInSNiOnrbOkQ-Q_w" "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/138.0.0.0 Safari/537.36 Edg/138.0.0.0"
2025-07-09T06:13:20.968Z info:  deserializeUser: c35f23dd-2732-46b7-9283-15b14eac234b
2025-07-09T06:13:21.478Z error: uncaughtException: Command failed: /home/hackmd/app/node_modules/phantomjs-prebuilt/lib/phantom/bin/phantomjs /home/hackmd/app/node_modules/markdown-pdf/phantom/render.js /tmp/tmp-<MASKED>.html /tmp/tmp-<MASKED>.pdf /home/hackmd/app /home/hackmd/app/node_modules/markdown-pdf/runnings.js /home/hackmd/app/node_modules/markdown-pdf/css/pdf.css /home/hackmd/app/node_modules/highlight.js/styles/github-gist.css A4 portrait 2cm 0 10000
PhantomJS has crashed. Please read the bug reporting guide at
<http://phantomjs.org/bug-reporting.html> and file a bug report.
Error: Command failed: /home/hackmd/app/node_modules/phantomjs-prebuilt/lib/phantom/bin/phantomjs /home/hackmd/app/node_modules/markdown-pdf/phantom/render.js /tmp/tmp-<MASKED>.html /tmp/tmp-<MASKED>.pdf /home/hackmd/app /home/hackmd/app/node_modules/markdown-pdf/runnings.js /home/hackmd/app/node_modules/markdown-pdf/css/pdf.css /home/hackmd/app/node_modules/highlight.js/styles/github-gist.css A4 portrait 2cm 0 10000
PhantomJS has crashed. Please read the bug reporting guide at
<http://phantomjs.org/bug-reporting.html> and file a bug report.
    at ChildProcess.exithandler (node:child_process:402:12)
    at ChildProcess.emit (node:events:513:28)
    at maybeClose (node:internal/child_process:1100:16)
    at Socket.<anonymous> (node:internal/child_process:458:11)
    at Socket.emit (node:events:513:28)
    at Pipe.<anonymous> (node:net:301:12)
2025-07-09T06:13:21.481Z error:  Process will exit now.
Info: try to connect to tcp://codimd_db in port 5432
2025/07/09 06:13:22 portchecker.go:56: dial tcp codimd_db:5432: connect: connection success

Possible cause / context

• Matches Rendering Emojis hajareshyam/pdf-creator-node#45 — PhantomJS cannot render certain emoji/Unicode glyphs.
• Removing all emoji lets the export succeed → strong evidence of an encoding issue.
• PhantomJS is unmaintained; CodiMD relies on it via markdown-pdf.

Potential solutions

1. Upgrade to CodiMD 3.x (if it has moved to a Chromium/Puppeteer backend).
2. Replace PhantomJS with Puppeteer/Playwright in a custom build.
3. Test latest phantomjs-prebuilt patch to confirm whether the crash persists.

Help wanted

• Can maintainers reproduce this crash with an emoji-containing note?
• Is there an official plan to migrate away from PhantomJS?
• Any patch or workaround would be greatly appreciated.