500 Status Code (Shufti Pro Error)

This error server encountered an unexpected condition which prevented it from fulfilling the request.

501 (Not implemented)

This status code suggests that the server does not support the functionality required to fulfill the
request. This is the appropriate response when the server does not recognize the request method
and is not capable of supporting it for any resource.

502 (Bad Gateway)

The server, while acting as a gateway or proxy, received an invalid response from the upstream
server it accessed in attempting to fulfill the request. This status code appears if the server was acting
as a gateway or proxy and received an invalid response from the upstream server.

503 (Service Unavailable)

The server is currently unable to handle the request due to a temporary overloading or maintenance of
the server. The implication is that this is a temporary condition which will be alleviated after some delay.