HTTP Error 406 - Not acceptable


A client can indicate to the Web server characteristics of the data it will accept back from the Web server. This is done using 'accept headers' of the following types:

If the Web server detects that the data it wants to return is not acceptable to the client, it returns a header containing the 406 error code.

406 errors in the HTTP cycle

Any client goes through the following cycle:

This error occurs in the final step above when the client receives an HTTP status code that it recognises as '406'.

Fixing 406 errors - general

This error occurs very infrequently in Web browsers, because most browsers will accept any data returned from your Web server.

If the client is not a Web browser, then anyone can only investigate the problem by looking at the Accept headers generated by the client system and the data stream returned by the Web server. If you do not have access to the source code for these systems, the only thing you can do is refer the problem to technical support people at the companies that developed the systems.