proxy_fcgi:error errors when using PHP-FPM

Symptoms

Your site displays "The timeout specified has expired"  or "504 Gateway timeout" and an entry similar to the following may be found in the Apache error log.

[Thu Nov 19 16:22:22.011567 2020] [proxy_fcgi:error] [pid 7442:tid 47611709007616] (70007)The timeout specified has expired: [client 203.0.113.2:11218] AH01075: Error dispatching request : (polling), referer: http://domain.tld/

Description 

The issue normally occurs when a script takes longer to complete than the ProxyTimeout value. The default ProxyTimeout value on a cPanel server is 300 seconds. Increasing the ProxyTimeout value can alleviate this issue.

Workaround

1. Access the server's command line as the 'root' user via SSH or "Terminal" in WHM.
2. Open /etc/apache2/conf.d/includes/pre_main_global.conf with your preferred text editor.
3. Add the following line to pre_main_global.conf if it doesn't exist.

   ProxyTimeout $timeout

   Please note that "$timeout" must be replaced with the new timeout value in seconds.
4. Restart Apache.

   /scripts/restartsrv_httpd

Additional resources

Include Editor