ErrorFindly
4064xx Client ErrorMedium

HTTP 406 Not Acceptable

Defined in RFC 7231

What Does HTTP 406 Mean?

The server cannot produce a response matching the acceptable values defined in the request's Accept headers.

Common Causes

  1. 1Accept header requests unsupported content type
  2. 2API doesn't support requested response format
  3. 3Content negotiation failure
  4. 4Accept-Language or Accept-Encoding mismatch

Impact

  • ⚠Content cannot be delivered in the requested format
  • ⚠API response format mismatch

Developer Fix

For web developers and application engineers

  1. 1Check and update Accept headers in requests
  2. 2Support multiple response formats in the API
  3. 3Remove overly restrictive Accept headers

Server Admin Fix

For system administrators and DevOps engineers

  1. 1Configure server to support common content types
  2. 2Implement content negotiation properly
  3. 3Return available content types in error response

Frequently Asked Questions

What does the Accept header do?
The Accept header tells the server what content types the client can handle (e.g., Accept: application/json). If the server can't produce any of those types, it returns 406.
How do I fix a 406 error?
Broaden your Accept header (e.g., use */* for any type), check what formats the API supports, or remove the Accept header to let the server choose the default format.

Related HTTP Status Codes

300Multiple Choices415Unsupported Media Type

About the Author

Web Infrastructure Team

Verified against official RFC specifications and real-world server configurations. HTTP status code behavior confirmed across Apache, Nginx, and Cloudflare.