Hi everyone,
We are using Nginx as reverse proxy.
From last 8-9months we are facing one issue in which nginx 500 response spike obseved. And we didnt see any call to upstream. It seems like Nginx caches the 500 response and that us served back to user.
We have to restart the Nginx every time when issue occurred.

As per Nginx Documentation by default nginx caches 200, 301 & 302 response
code but we are observing that if Upstream server gives error 400 or 500 or
503, etc , response is getting cached and all other requests for same file becomes HIT.

Though if we set proxy_cache_valid specifying response code ( like
proxy_cache_valid 200 15m; ) then also its caching the error response code
but its not caching 301 & 302 in that case. Why the same is not getting applied for error response code.

Please advise to resolve this issue.

Thanks,