The HTTP510 Not Extendedserver error response status code is sent when the client request declares an HTTP Extension (RFC 2774) that should be used to process the request, but the extension is not supported.

Status

510 Not Extended

Examples

Extension not supported

In the following example, a client sends a request with a mandatory extension specified in theC-MAN header.TheConnection header specifies that these extensions are to be handled on ahop-by-hop basis.Aproxy forwards the extended request, but theConnection header is stripped out in transit.Because the origin server doesn't receive any information about theM-GET method, it sends a510 in response:

M-GET /document HTTP/1.1Host: example.comC-Man: "http://www.example.org/"Connection: C-Man

HTTP/1.1 510 Not Extended

Specifications

See also

• HTTP response status codes