PHP FPM 503 errors on websites that do not have PHP FPM enabled from WHM or cPanel

Symptoms

You may find that a website is producing "503 Service Unavailable" errors when you visit your browser.

In this situation you would also find a corresponding log very similar to the following in the Apache error log:

/etc/apache2/logs/error_log

[Wed Mar 31 03:19:07.111327 2021] [proxy_fcgi:error] [pid 17628] [client xxx.xxx.xxx.xxx:0] AH01079: failed to make connection to backend: httpd-UDS

When checking the WHM at:

Home »Software »MultiPHP Manager

The domain that is having the problem shows that PHP FPM is disabled or unavailable for the domain.

If your situation matches those three conditions, you may find the resolution on this article helpful.

Description 

If PHP FPM was disabled incorrectly, or a problem occurred on the server that left cruft PHP FPM configuration files in place when they should not be there, it could cause this problem to occur.

Resolution

1. Login to the server via SSH or Terminal as the root user

2. Verify that cruft files exist and find their locations by running the following command:

/usr/local/cpanel/scripts/php_fpm_config --check

3. If that command shows a list of cruft files at the end, you must either delete or move th files to a different location on the server. It is recommended to move the files out of the way so that you may examine or restore the files later if needed.

4. Once the files have been moved out of the way, issue the following command to rebuild the FPM configuration and restart Apache:

/usr/local/cpanel/scripts/php_fpm_config --rebuild --check

5. Visit your domain to confirm that the 503 error has been resolved