The HTTP
406 Not Acceptable
client error response
status code indicates that the server could not produce a response matching the list of acceptable values defined in the request's
proactive content negotiation
headers and that the server was unwilling to supply a default representation.
Proactive content negotiation headers include:
Accept
Accept-Encoding
Accept-Language
A server may return responses that differ from the request's accept headers.
In such cases, a
200
response with a default resource that doesn't match the client's list of acceptable content negotiation values may be preferable to sending a 406 response.
If a server returns a 406, the body of the message should contain the list of available representations for the resource, allowing the user to choose, although no standard way for this is defined.
The following request assumes that
www.example.com/docs/doc1
supports sending a document back as
application/rtf
:
GET /docs/doc1 HTTP/1.1
Host: example.com
Accept: application/rtf;
In this example, the server implementation does not fallback to a default content type like text/html or application/json, but returns a 406 instead:
