(52) Empty reply from server on slow response

[ktiniatros]

Hi,

I have a node.js/express backend with nginx. Everything works fine except
one request which gives back (52) Empty reply from server on slow responses
ONLY (this request aggregates remote data, so in some very specific
scenarios it takes time to complete). By slow, I mean specifically when the
response takes more than 4 minutes (node.js still working since I see its
log but nginx is already closing the request with the above message). 

Anyone has an idea why this is happening ? And what's the proper way to
debug this kind of issues ?

Thank you in advance for your time.

Posted at Nginx Forum: https://forum.nginx.org/read.php?2,267819,267819#msg-267819