When the following error appears in the domain's error log /var/www/vhosts/system/example.com/logs/error_log:
[proxy:error] [pid 7314] (2)No such file or directory: AH02454: FCGI: attempt to connect to Unix domain socket /var/www/vhosts/system/example.com/php-fpm.sock (*) failed
Or
[proxy:error] [pid 15065:tid 139826443527936] (111)Connection refused: AH02454: FCGI: attempt to connect to Unix domain socket /data/vhosts/system/example.com/php-fpm.sock (*) failed
[proxy_fcgi:error] [pid 15065:tid 139826443527936] [client 203.0.113.2:50232] AH01079: failed to make connection to backend: httpd-UDS
The cause of the problem mentioned above is probably Pool configuration file is missing or corrupted.
Resolution
Regenerate the configuration:
Log into Plesk.
Go to Plesk > Domains > example.com > PHP Settings and click OK:
If multiple domains are affected:
1. Connect to the server via SSH;
2. Execute the following command to update settings on all domains:
# /usr/local/psa/bin/php_settings -u
