Chrome ERR_HTTP2_PROTOCOL_ERROR when submitting multipart/form-data to n8n form endpoint (Production only)

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Aaster-ncyDEVELOPER2/20/2026

Hi Zeabur team,

I’m experiencing a Chrome-specific HTTP/2 issue when submitting a multipart form upload to an n8n instance hosted on Zeabur.

The same workflow works correctly in:

Firefox
Comet browser
n8n test execution mode

But fails in Chrome (including Incognito mode) in production.

Environment

Hosting: Zeabur
Service: n8n
Public URL: https://sg-automation.zeabur.app
n8n version: (latest, recently updated)
Deployment: Production
Protocol: HTTPS
N8N_TRUST_PROXY=true
N8N_PROTOCOL=https
WEBHOOK_URL set correctly to public domain

Issue Details

When submitting a file upload form:

POST https://sg-automation.zeabur.app/form/96f259f2-747f-46b8-a9b6-aa47cf4e35a7

Chrome fails with:

net::ERR_HTTP2_PROTOCOL_ERROR
TypeError: Failed to fetch

From DevTools:

Protocol: h2
Content-Type: multipart/form-data
Content-Length: ~700KB
Origin: null
Sec-Fetch-Site: cross-site

The request fails before reaching the n8n workflow logic.

Important Observations

Works in Firefox
Works in other browsers
Only fails in Chrome
Only fails in production
n8n test execution works
The issue appears to happen at HTTP/2 layer
The form upload size is below 1MB

This suggests a possible issue with:

HTTP/2 stream handling
multipart upload handling
edge proxy framing
TLS/ALPN negotiation
request termination under HTTP/2

What I Need Clarified

Is there any known HTTP/2 issue with multipart/form-data uploads on Zeabur?
Is there a way to:

Disable HTTP/2?
Force HTTP/1.1?
Adjust proxy buffering settings?

Is there any size threshold that triggers this?
Are there edge logs available for failed HTTP2 streams?

Reproduction Steps

Open Chrome
Navigate to form endpoint
Upload ~500KB–1MB image
Click submit
Observe ERR_HTTP2_PROTOCOL_ERROR

Firefox does not reproduce this issue.

Expected Behavior

Chrome should successfully POST multipart/form-data to n8n endpoint without HTTP/2 protocol error.

Thank you in advance 🙏

2 Replies

Aaster-ncyDEVELOPER2/20/2026

Update (Feb 21): Issue also confirmed on Windows Edge, not just Chrome. Both Chrome and Edge on Windows fail, while macOS Chrome works fine. This confirms the issue is at the Windows network stack / HTTP/2 layer, not browser-specific. Also confirmed that the Nginx config file at /etc/nginx/conf.d/n8n.conf with proxy_http_version 1.1 and proxy_request_buffering off does not resolve the issue, suggesting Zeabur's edge proxy handles HTTP/2 termination before the internal Nginx config is applied.

Update — Root Cause Confirmed (Feb 21)

After extensive testing tonight, I can now confirm the root cause with certainty.

New Findings

Issue is not Chrome-specific — it affects all Windows browsers:

Windows Chrome ❌
Windows Edge ❌
macOS Chrome ✅
Firefox (all platforms) ✅

This confirms it is a Windows network stack issue, not a browser-specific one. Chrome and Edge on Windows share the same underlying HTTP/2 implementation, which behaves differently from macOS Chrome.

Definitive Proof

I tested by launching Chrome with the --disable-http2 flag:

chrome.exe --disable-http2

Result: Form submission works perfectly on Windows Chrome with HTTP/2 disabled.

File uploads successfully ✅
Workflow completes without errors ✅
No ERR_HTTP2_PROTOCOL_ERROR ✅

This proves the issue is 100% at the HTTP/2 layer of the edge proxy, not in the n8n workflow or application logic.

What I've Already Tried

Added Nginx config via Config Editor (/etc/nginx/conf.d/n8n.conf) with proxy_http_version 1.1 and proxy_request_buffering off → no effect (Zeabur's edge proxy handles the connection before internal Nginx)
Updated all relevant n8n environment variables → no effect
Tested on different networks → same result

Root Cause Summary

Zeabur's edge proxy terminates connections over HTTP/2. Windows Chrome/Edge use a stricter HTTP/2 implementation than macOS Chrome, causing the multipart/form-data upload to fail at the edge proxy before it even reaches n8n.

Specific Request

Could you please do one of the following for sg-automation.zeabur.app:

Disable HTTP/2 at the edge proxy level, or
Force HTTP/1.1 for incoming connections, or
Enable proxy_request_buffering off at the edge proxy level

Any one of these would permanently resolve the issue for all Windows users.

Thank you 🙏

Latest Update (Feb 21, late night)

Windows Chrome is now working unexpectedly — the ERR_HTTP2_PROTOCOL_ERROR has disappeared without any additional changes on my end.

Current status:

Windows Chrome ✅ resolved (unknown what fixed it)
macOS Chrome ✅ works
Firefox ✅ works
Windows Edge ❌ still fails with ERR_HTTP2_PROTOCOL_ERROR

Could you clarify if any infrastructure changes were made on Zeabur's side that may have resolved Chrome? And can the same fix be applied for Windows Edge?

Thank you 🙏

Aaster-ncyDEVELOPER2/23/2026

Hi, the ERR_HTTP2_PROTOCOL_ERROR appears again T ^T
Could you please help on this issue? Many thanks to Zeabur team