501
Not Implemented
5xx Server error
Class
RFC 9110 §15.6.2
Defined in
What does HTTP 501 mean?
The server does not support the functionality required to fulfil the request. Usually means the HTTP method is unknown to the server entirely (as opposed to 405, where the server knows the method but the resource does not allow it).
5xx Server error: The request looked valid, but the server failed to fulfil it. The fix is on the server side.
How to fix 501 Not Implemented
- Use a standard method the server supports.
501 and SEO
Pages returning 501 are not indexed.
Example response
HTTP/1.1 501 Not ImplementedRelated status codes
- 405 Method Not Allowed — The URL exists, but does not support the HTTP method used.
- 500 Internal Server Error — The server hit an unexpected condition and could not complete the request.
Check which status code a URL returns with the HTTP header checker.
All HTTP status codesSearch the full list of status codes from 100 to 599 with their meanings and SEO impact.
Open the full list Frequently asked questions
What does status code 501 mean?
501 Not Implemented: The server does not support the functionality required to fulfil the request.
How do I fix a 501 error?
Use a standard method the server supports.
Does 501 affect SEO?
Pages returning 501 are not indexed.