4xx Client Error

HTTP 406 Not Acceptable

The server cannot produce a response matching the Accept headers sent by the client. The requested content negotiation failed because none of the available representations match the client's criteria.

Common Causes

  • Accept header requests a format the server doesn't support
  • Accept-Language specifies an unavailable language
  • Content negotiation failed between client and server

How to Fix

  1. 1Adjust the Accept header to match server capabilities
  2. 2Remove restrictive Accept headers to allow any format
  3. 3Check API docs for supported response formats

Example

HTTP 406 Not Acceptable
GET /api/data HTTP/1.1
Accept: application/xml

→ 406 Not Acceptable
→ Server only supports application/json

Related Client Error Codes

400

Bad Request

401

Unauthorized

402

Payment Required

403

Forbidden

404

Not Found

405

Method Not Allowed

407

Proxy Authentication Required

408

Request Timeout

409

Conflict

410

Gone

411

Length Required

412

Precondition Failed

413

Content Too Large

414

URI Too Long

415

Unsupported Media Type

416

Range Not Satisfiable

417

Expectation Failed

418

I'm a Teapot

421

Misdirected Request

422

Unprocessable Content

423

Locked

424

Failed Dependency

425

Too Early

426

Upgrade Required

428

Precondition Required

429

Too Many Requests

431

Request Header Fields Too Large

451

Unavailable For Legal Reasons