// http 4xx · client error
HTTP 406 Not Acceptable
Can't produce a response matching the Accept headers.
What HTTP 406 Not Acceptable means
406 Not Acceptable means the server can't produce a response in any format the client said it would accept via the `Accept` header. It's rare in practice — most servers fall back to a default format instead.
Which category is it?
406 is a 4xx code — Client error. 4xx means the request has a problem the client must fix — bad syntax, missing authentication, or a resource that isn't there. It's the caller's responsibility.
Common causes
- `Accept` header requests a format the server can't produce
- Overly strict content negotiation
How to fix it
- Relax or correct the `Accept` header
- Request a format the server supports (e.g. `application/json`)