Not Implemented

What does HTTP 501 Not Implemented mean?

The server does not support the functionality required to fulfil the request — for example, an unrecognized request method. It implies the capability may be added in the future.

5xx responses indicate the server failed to fulfil a valid request. The problem is on the server side and is not something the client can fix by changing the request.

Example

PATCH /resource HTTP/1.1

→ HTTP/1.1 501 Not Implemented

Common causes

• The server does not recognize or support the request method
• A feature or endpoint has not been implemented yet
• A proxy does not support a required capability

How to fix a 501 error

• Use a supported HTTP method for the endpoint
• Confirm the feature is actually implemented on the server
• Check API documentation for supported operations

Related 5xx status codes