Upstream too big - nginx + codeigniter

Question

I am getting this error from Nginx, but can't seem to figure it out! I am using codeigniter and am using the database for sessions. So I'm wondering how the header can ever be too big. Is there anyway to check what the header is? or potentially see what I can do to fix this error?

Let me know if you need me to put up any conf files or whatever and I'll update as you request them

2012/12/15 11:51:39 [error] 2007#0: *5778 upstream sent too big header while reading response header from upstream, client: 24.63.77.149, server: jdobres.xxxx.com, request: "POST /main/login HTTP/1.1", upstream: "fastcgi://127.0.0.1:9000", host: "jdobres.xxxxx.com", referrer: "http://jdobres.xxxx.com/"

UPDATE

I added the following into conf:

proxy_buffer_size   512k;
proxy_buffers   4 512k;
proxy_busy_buffers_size   512k;

And now I still get the following:

2012/12/16 12:40:27 [error] 31235#0: *929 upstream sent too big header while reading response header from upstream, client: 24.63.77.149, server: jdobres.xxxx.com, request: "POST /main/login HTTP/1.1", upstream: "fastcgi://127.0.0.1:9000", host: "jdobres.xxxx.com", referrer: "http://jdobres.xxxx.com/"

Answer 1

Add this to your http {} of the nginx.conf file normally located at /etc/nginx/nginx.conf:

proxy_buffer_size   128k;
proxy_buffers   4 256k;
proxy_busy_buffers_size   256k;

Then add this to your php location block, this will be located in your vhost file look for the block that begins with location ~ .php$ {

fastcgi_buffer_size 128k;
fastcgi_buffers 4 256k;
fastcgi_busy_buffers_size 256k;