upstream sent too big header while reading response header from upstream

Question

I am getting these kind of errors:

2014/05/24 11:49:06 [error] 8376#0: *54031 upstream sent too big header while reading response header from upstream

Answer 1

Plesk instructions

In Plesk 12, I had nginx running as a reverse proxy (which I think is the default). So the current top answer doesn't work as nginx is also being run as a proxy.

I went to Subscriptions | [subscription domain] | Websites & Domains (tab) | [Virtual Host domain] | Web Server Settings.

Then at the bottom of that page you can set the Additional nginx directives which I set to be a combination of the top two answers here:

fastcgi_buffers 16 16k;
fastcgi_buffer_size 32k;
proxy_buffer_size   128k;
proxy_buffers   4 256k;
proxy_busy_buffers_size   256k;