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

**URL:** <https://discourse.mailinabox.email/t/connection-error-failed-to-reach-the-server-on-roundcube-attachment-upload-only-in-chrome-chromium-status-0-works-fine-in-firefox/16278>\
**Category:** uncategorized\
**Created:** [February 27, 2026, 10:10am UTC](https://discourse.mailinabox.email/t/connection-error-failed-to-reach-the-server-on-roundcube-attachment-upload-only-in-chrome-chromium-status-0-works-fine-in-firefox/16278 "2026-02-27T10:10:17Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Feydreva](https://discourse.mailinabox.email/letter_avatar_proxy/v4/letter/f/45deac/32.png) [@Feydreva](https://discourse.mailinabox.email/u/Feydreva)\
**Post date:** [February 27, 2026, 10:10am UTC](https://discourse.mailinabox.email/t/connection-error-failed-to-reach-the-server-on-roundcube-attachment-upload-only-in-chrome-chromium-status-0-works-fine-in-firefox/16278/1 "2026-02-27T10:10:17Z")

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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). 

- 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:

```auto
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 ?

---

<div class="post-metadata">

**Author:** ![KiekerJan](https://discourse.mailinabox.email/user_avatar/discourse.mailinabox.email/kiekerjan/32/2339_2.png) [@KiekerJan](https://discourse.mailinabox.email/u/KiekerJan)\
**Post date:** [February 27, 2026, 4:50pm UTC](https://discourse.mailinabox.email/t/connection-error-failed-to-reach-the-server-on-roundcube-attachment-upload-only-in-chrome-chromium-status-0-works-fine-in-firefox/16278/2 "2026-02-27T16:50:49Z")

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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.