When requesting information from the server, the browser or client also includes a specification with its request for the format in which it wants the information returned.
If the server is unable to accommodate this request it will return a 406 Not Acceptable error page. This error occurs very infrequently in Web browsers, because most browsers will accept any data returned from the Web server.
If you experience this error, you would need to refer to the technical support for the client sending the request.