"Connection error, failed to reach the server" on Roundcube attachment upload ONLY in Chrome/Chromium (status 0), works fine in Firefox

1

Hello,

I’m facing a specific issue with Roundcube webmail: attachment upload fails ONLY in Chrome/Chromium with “Connection error, failed to reach the server”, but works perfectly in Firefox. All other features (reading, sending without attachments, etc.) work fine in both browsers.

Technical details:

  • Network tab (F12): ?_task=mail&_action=upload request → status (failed) / code 0 (no server response).

    image
    image1200×518 121 KB

  • Tested with files <1MB.

Tests performed (none fixed it):

  • Incognito mode (Ctrl+Shift+N)
  • All extensions disabled (chrome://extensions)
  • Cache/cookies cleared for domain (chrome://settings/content/all)
  • No VPN/proxy active

System info:

  • OS: Linux Arch
  • Chrome/Chromium version: 145.0.7632.116
  • Launched Chrome clean:
chromium --no-sandbox --disable-web-security --disable-features=VizDisplayCompositor --user-data-dir=/tmp/chrome-test

→ Still status 0 error.

Anyone seen this Chrome-specific bug?
Any idea on how to solve this ?

2

I have no solution for this. But you might check

  • The roundcube github issue tracker. Maybe somebody has reported this
  • There should be a roundcube log on your server. Maybe it has more details. Also try to find the php log.