501
Not Implemented
Server errors (5xx)·RFC 9110
What 501 means
The server does not support the functionality required to fulfil the request.
Returned when the server does not recognize the request method or lacks the ability to handle it.
Server errors (5xx)
The server failed to fulfil an apparently valid request.
Other 5xx codes
FAQ — 501
What does HTTP 501 mean?
501 Not Implemented: The server does not support the functionality required to fulfil the request. Returned when the server does not recognize the request method or lacks the ability to handle it.
Which class does status code 501 belong to?
501 is a Server errors (5xx) code. The server failed to fulfil an apparently valid request.
Where is the 501 code defined?
Status code 501 is defined in RFC 9110 and is part of the IANA HTTP Status Code Registry.