We were setting up a new server with NGINX in reverse proxy when we got the dreaded 502 | Bad Gateway error.
Checking the NGINX error log gave us the following error:
upstream sent too big header while reading response header from upstream
This occurs when NGINX receives a header from the upstream server that is larger than it is configured to handle. This is fairly simple to fix, though you may need to play around with the settings to see which suits you best.
For us, we added the following 3 lines to our NGINX vhost file for the website inside the location block under the server block
proxy_busy_buffers_size 512k; proxy_buffers 4 512k; proxy_buffer_size 256k;
Next, restart NGINX.
sudo service nginx restart
That’s it, you’re done