510 Not Extended
Description
The HTTP 510 Not Extended
response status code is sent in the context of the HTTP Extension Framework, defined in
RFC 2774.
In that specification a client may send a request that contains an extension
declaration, that describes the extension to be used. If the server receives such a
request, but any described extensions are not supported for the request, then the server responds with the 510 status code.
See Also
Source: https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/510
