5xx Server Errors
These status codes indicate that the server is aware that it has encountered an error or is otherwise incapable of performing the request. The problem is on the server side — the client's request may be valid, but the server failed to fulfill it due to an internal issue, overload, or configuration problem.
500
Internal Server ErrorA generic error message when the server encounters an unexpected condition that prevents it from fulfilling the request.
501
Not ImplementedThe server does not support the functionality required to fulfill the request (e.g., an unsupported HTTP method).
502
Bad GatewayThe server, acting as a gateway or proxy, received an invalid response from an upstream server.
503
Service UnavailableThe server is not ready to handle the request, usually due to maintenance, overload, or being temporarily disabled.
504
Gateway TimeoutThe server, acting as a gateway, did not receive a timely response from an upstream server.
505
HTTP Version Not SupportedThe server does not support the HTTP protocol version used in the request.
506
Variant Also NegotiatesTransparent content negotiation for the request results in a circular reference.
507
Insufficient StorageThe server is unable to store the representation needed to complete the request (WebDAV).
508
Loop DetectedThe server detected an infinite loop while processing the request (WebDAV).
510
Not ExtendedFurther extensions to the request are required for the server to fulfill it.
511
Network Authentication RequiredThe client must authenticate to gain network access (e.g., captive portal).