Nginx upstream sent too big header while reading response header from upstream

I came accross a very strange issue while deploying a vagrant development box. The application that was shown properly in Safari, but gave a 500 when I opened it with Chrome.

I found the following error:

upstream sent too big header while reading response header from upstream

It says that the response header from fastcgi upstream is too big and Nginx can’t process it. I increased the Nginx buffers to fix this.

fastcgi_buffers 16 16k;
fastcgi_buffer_size 32k;

You might also have this issue when running Nginx as a proxy, easy to fix:

proxy_buffers 8 16k;
proxy_buffer_size 32k;

Thanks for reading

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