501 Not Implemented
5xx Server Error
RFC 9110
The server doesn't know how to handle this method.
What 501 Not Implemented means {#what}
The HTTP method used in the request is not recognized or supported by the server at all — not just for this route, but globally. Only GET and HEAD are required to be supported. Distinct from 405, which is about a specific resource not supporting a method.
When you’ll see a 501 {#when}
- Using an unusual HTTP method a server doesn’t recognize
- Incomplete server implementations