Yes. 5xx codes are server errors: The server failed to fulfil a valid-looking request.

5xx · Server error

HTTP 510 Not Extended

Further extensions to the request are required for the server to fulfil it.

Example response

HTTP

HTTP/1.1 510 Not Extended
Content-Type: application/json; charset=utf-8

{ "error": "Not Extended" }

Look up the headers shown here in the HTTP headers reference.

What does HTTP 510 mean?: Not Extended. Further extensions to the request are required for the server to fulfil it.
Is 510 an error?: Yes. 5xx codes are server errors: The server failed to fulfil a valid-looking request.