Nginx 1.28.0 breaks Cloudflare Proxying

Troubleshooting
1

My issue:
After upgrading nginx from 1.26.3-r0 → 1.28.0-r3, it breaks Cloudflare proxying and the client receives an HTTP 525 error. This was working fine with nginx 1.26.3 before the upgrade.

How I encountered the problem:
I upgraded nginx from 1.26.3-r0 → 1.28.0-r3, which then broke Cloudflare proxying and the client receives an HTTP 525 error.

Solutions I’ve tried:
Turned off CF proxy and then nginx 1.28.0 works, but it’s not clear what broke in 1.28.0 that was working fine in the previous version of nginx 1.26.3.

Version of NGINX or NGINX adjacent software (e.g. NGINX Gateway Fabric):
nginx 1.28.0

Deployment environment:
Alpine Linux

Minimal NGINX config to reproduce your issue (preferably running on https://tech-playground.com/playgrounds/nginx for ease of debugging, and if not as a code block): (Tip → Run nginx -T to print your entire NGINX config to your terminal.)

NGINX access/error log: (Tip → You can usually find the logs in the /var/log/nginx directory.)

2

Hey @jgreyz! The first thing that comes to mind is that it seems as if you are using the NGINX build provided by Alpine instead of us proper. Can you try following the steps here to install the package built by us and see if you are still running into the same issue?