Domains on PHP-FPM do not work with error 503 after changing virtual hosts location: the prefix ‘/var/www/vhosts/system/example.com’ does not exist or is not a directory

Symptoms

• After changing the virtual hosts location or mounting the new disk to the directory /var/www/vhosts or changing PHP handler via CLI, the websites which use PHP-FPM are not working with the error 503.

• The PHP-FPM service is down with the following error in its log file (/var/log/plesk-phpXX-fpm/error.log in case of PHP shipped by Plesk, where XX is a PHP version; /var/log/php-fpm.log, /var/log/php5-fpm.log or /var/log/php7.0-fpm.log in case of PHP by OS vendor):

  ERROR: [pool example.com] the prefix '/var/www/vhosts/system/example.com' does not exist or is not a directory
   ERROR: failed to post process the configuration 
   ERROR: FPM initialization failed

Cause

PHP configurations for domains were not updated after changing virtual hosts location or mounting the new disk.

Resolution

1. Connect to the server using SSH.

2. Update PHP configuration using the following command:

   # plesk bin php_settings -u