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.)