5xx Server Errors
- 500 Internal Server Error
This code is the default for an error condition when none of the other 5xx codes apply.
- 501 Not Implemented
This code indicates that the server does not implement the necessary features to satisfy the request.
- 502 Bad Gateway
This code indicates that the server received an invalid response from an upstream server.
- 503 Service Unavailable
This code indicates that the server is temporarily unable to process the client’s request. A server that becomes overloaded may use this code to let the client know that it can retry the request later.
- 504 Gateway Time-out
This code is used by proxies and some servers to indicate a timeout when forwarding the client’s request. It’s also used when a request with the
only-if-cacheddirective would result in a cache miss.- 505 HTTP Version Not Supported
This code indicates that the server refuses to handle this request because of the HTTP version in the request line.