> Most likely you are trying to configure
> client_header_buffer_size/large_client_header_buff
> ers in a pure
> virtual server{}. This won't work as request
> headers parsing
> happens before Host header is known (and virtual
> server is
> selected), hence parseing happens in a context of
> the default
> server for a listen socket.
>
> You have to configure
> client_header_buffer_size/large_client_header_buff
> ers
> in a default server (or at http level).
>

I tried to set it in the http context of the main /etc/nginx/nginx.conf file:

http {
large_client_header_buffers 8 512k;

...
include /etc/nginx/sites-enabled/*;
}

And my server contexts are defined in a conf file in sites-enabled. But large_client_header_buffers still appears to be ignored.