Problem:
[proxy_fcgi:error] [pid 3659] (70007)The timeout specified has expired: [client :39524] AH01075: Error dispatching request to : (polling)
Solution:
vim /etc/httpd/conf/httpd.conf
Timeout 600
systemctl reload httpd
Reference: https://stackoverflow.com/questions/46594731/php-apache-error-dispatching-request