HTTP - status: 406 Not Acceptable
In this short article we would like to explain what 406 Not Acceptable status means in HTTP response and when occurs.
When server returns status 406 for HTTP request (Not Acceptable) it means the server is not albe to match acceptable values located in headers in client request.
During negotation can be used following headers:
AcceptAccept-CharsetAccept-EncodingAccept-Language
Let's suppose client sends following headers (user web browser tells that is able to handle only value combinations from headers):
xxxxxxxxxxAccept: application/jsonAccept-Charset: utf-8, iso-8859-1;q=0.5Accept-Encoding: gzip, deflateAccept-Language: en-US,en;q=0.9Server is not able to provide any combination from Accept citeria and returns 406 status.
Any combination means:
xxxxxxxxxxAccept Accept-Charset Accept-Encoding Accept-Languageapplication/json utf-8 gzip en-USapplication/json utf-8 deflate en-USapplication/json iso-8859-1 deflate enetc.Example web browser request:
xxxxxxxxxxGET /backend/45a62d3d/download HTTP/1.1Host: 192.168.0.50:8080Connection: keep-alivePragma: no-cacheCache-Control: no-cacheAccept: application/jsonUser-Agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/84.0.4147.105 Safari/537.36Content-Type: application/jsonOrigin: http://localhost:8000Referer: http://localhost:8000/downloadsAccept-Charset: utf-8, iso-8859-1;q=0.5Accept-Encoding: gzip, deflateAccept-Language: en-US,en;q=0.9Example server response:
xxxxxxxxxxHTTP/1.1 406Server: nginx/1.18.0Date: Wed, 02 Sep 2020 09:46:31 GMTContent-Length: 0Connection: keep-aliveCache-Control: privateExpires: Thu, 01 Jan 1970 00:00:00 GMTAccess-Control-Allow-Origin: http://localhost:8000Access-Control-Allow-Credentials: trueAmount of reasones why server is not able to proceed with user requirements can be different, but as example we can use: lack of support for application/json MIME type - user expected JSON response for XHR / Ajax request.
Solutions:
- as server owner you can provide following response by proper response implementation,
- or requester can change request requirements and asks with different MIME type.
