The following error displays on 'Websites' tab when managing website's settings:
Error: Unable to create or update the subscription: The PHP handler "fastcgi" is not registered. It was probably deleted from the server. Register a handler with the same properties and try again.
fastcgi PHP handler was removed.
Register the missing PHP handler:
# /usr/local/psa/bin/php_handler --add -id fastcgi -displayname 5.3 -path /usr/bin/php-cgi -phpini /etc/php.ini -type fastcgi -service-node 203.0.113.2
203.0.113.2 - IP address of the service node where the websites is hosting,
displayname - PHP version