[Solved] FastCGI, Drupal, Nginx, PHP7.2-FPM Error upstream sent too big header while reading response header from upstream

When you try to load Drupal Web app on Nginx and Nginx Web server through an error: Upstream sent too big header while reading response header from upstream, client: IP-Address, server: ServerName, Request


Problem:

The problem is that Nginx is not configured to wait for FastCGI a PHP processor to respond, chances are that Nginx has a time-out limit defined in its config file. 

Solution:

Just add these lines of code inside the http block in nginx.conf file : client_max_body_size 500M; fastcgi_buffer 8 16k; fastcgi_buffer_size 32k;