Client closed connection: 400 vs 499

Maxim Dounin mdounin at
Mon Jun 15 14:25:51 UTC 2015


On Mon, Jun 15, 2015 at 11:20:15AM +0300, Sorin Manole wrote:

> Hello,
> It seems that if the client closes the connection during a requests there
> are time when the request is logged as 400 and other times as 499.
> Is there a reason for the difference? Serving of the error page cannot be
> it because the connection is closed anyway.

The "400" code means that no correct request was received - that 
is, client sent a bad request.

The "499" code means that nginx got a request, but wasn't able to 
send a response.  That is, client closed connection before we 
started sending a response.  This, in particular, may happen if a 
backend is slow and nginx isn't able to return a response before 
the client times out.

The difference may be important when looking into logs.

Maxim Dounin

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