Service Unavailable

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.

While accessing one of the website saw the error mentioned above

Normally this 503 error are related to module PHP-fpm.

You just need to restart it from WHM to fix the issue