5xx Server Error

The server failed to fulfill a valid request. 500, 502, and 503 are the classic examples.

500Internal Server Error CommonA generic catch-all: the server hit an unexpected condition and could not complete the request.501Not ImplementedThe server does not support the functionality required to fulfill the request.502Bad Gateway CommonA gateway or proxy received an invalid response from an upstream server.503Service Unavailable CommonThe server is temporarily unable to handle the request due to overload or maintenance.504Gateway Timeout CommonA gateway or proxy did not get a timely response from an upstream server.505HTTP Version Not SupportedThe server does not support the major HTTP version used in the request.506Variant Also NegotiatesA server configuration error: the chosen variant is itself engaged in content negotiation.507Insufficient StorageThe server cannot store the representation needed to complete the request.508Loop DetectedThe server detected an infinite loop while processing the request.510Not ExtendedFurther extensions to the request are required for the server to fulfill it.511Network Authentication RequiredThe client needs to authenticate to gain network access (e.g. a captive portal).