You got http 504 gateway time out error in browser when visiting your wordpress site, and you see fcgi timeout error like follows in /usr/local/apache/logs/error_log
[proxy_fcgi:error] (70007)The timeout specified has expired: [client xxx.xxx.xxx.xxx:8959] AH01075: Error dispatching request to : (polling)
To fix this, you need to increase the TimeOut and ProxyTimeout in Apache Configuration file. It’s best to change this for an individual user than in global virtual host file.
Eg: the cpanel user id is “USERNAME”
You need to create file /etc/apache2/conf.d/userdata/ssl/2_4/USERNAME/php-fpm.conf, then add following two lines to overwrite the default settings.