I use proxy_cache_use_stale with updating attribute.
I grep my logs for the $upstream_cache_status UPDATING value and found many matchs but I can't reproduce this situation.
Can you please help to create conditions that leads me to the UPDATING in $upstream_cache_status ?! This is first step for me to find out why 500 instead of 200 returned to client.
Usual log line looks like:
... "GET / HTTP/1.1" 500 1208 "-" ... - - upstream_cache_status:UPDATING
So, the error code 500 returned to the client ;( By the documentation this should be the cached page and 200 code AFAIR.
What can lead to this issue?
I checked that nginx cache dir have enough space and files inside it not managed by any external utilities. No errors in error logs.