Front desk · HTTP Status Codes
5×× Server Error
510 Not Extended (OBSOLETED)
· filed 2026-07-18 · click a code to copy
HTTP 510 Not Extended (OBSOLETED) is a server error-class status code defined in RFC2774][Status change of HTTP experiments to Historic. Further extensions to the request are required for the server to fulfil it.
Server-error responses admit the fault is on the server's side: the request was valid, but the server failed to fulfil it. On the wire, the response begins with the status line HTTP/1.1 510 Not Extended (OBSOLETED).