Failed to Make Connection to Backend: httpd-UDS

Symptoms

When loading a domain within a browser, you may receive the following error: 

CONFIG_TEXT: Service Unavailable

The server is temporarily unable to service your request due to maintenance downtime or capacity problems. Please try again later.

Additionally, a 503 Service Unavailable error was encountered while trying to use an ErrorDocument to handle the request.

Upon checking the Apache error log, the following error is appended:

CONFIG_TEXT: [proxy_fcgi:error] [pid 8094] [client $IP:58140] AH01079: failed to make connection to backend: httpd-UDS, referer: http://domain.tld/wp-admin/
[proxy:error] [pid 8094] (13)Permission denied: AH02454: FCGI: attempt to connect to Unix domain socket /opt/cpanel/ea-php72/root/usr/var/run/php-fpm/a1ba87f4b576cd4f8722c78753deae434bb9b122.sock (*) failed

Cause

This can be caused when there is a communication error between PHP-FPM and Apache, resulting in Apache being unable to serve the request. 

Workaround

Pass a restart to the apache_php_fpm service using the following script: 

# /scripts/restartsrv_apache_php_fpm