406 Not Acceptable

HTTP 406 Not Acceptable means the server cannot generate a response that matches the criteria specified in the request's Accept, Accept-Charset, Accept-Encoding, or Accept-Language headers.

Strict content negotiation when the server has no representation that satisfies the client's preferences.

• Client requested Accept: application/xml but server only returns JSON
• Accept-Language for an unsupported locale
• Accept-Encoding for unsupported compression

• Add support for the requested format on the server
• Loosen Accept header restrictions on the client
• Implement format fallbacks (e.g., default to JSON if XML unsupported)

HTTP/1.1 406 Not Acceptable
Content-Type: application/json

{"error":"Only application/json supported"}