Status code 0

[Maxim Dounin]

Hello!

On Sat, May 04, 2024 at 07:31:43PM +0200, Sébastien Rebecchi wrote:

> Hello
> 
> What does it mean when nginx returns an http status code 0?
> 
> We see that cause we monitor nginx response status code, which is used as
> front of our apps. The apps themselves can not return 0, only 200 or 500.
> So it seems issue here comes from nginx itself which can not process the
> connection under high peak of load, but why 0, is that expected?

Status code 0 as seen in nginx http access logs means that nginx 
wasn't able to generate any reasonable status code, even some 
generic failure like 500 (Internal Server Error), yet the request 
was closed.

This usually happens due to some fatal issues, like unexpected 
conditions (which might indicate a bug somewhere), unexpected 
errors, or memory allocation errors if it wasn't possible to 
return 500.

In most cases there should be additional details in the error log 
explaining the reasons.  If there aren't any, or reasons aren't 
clear, it might be a good idea to dig further.

-- 
Maxim Dounin
http://mdounin.ru/