HTTP Error Code 406, Not Acceptable
Web browsers request for information from the server, and when it is performed, it sends an Accept header. In case if the server is not able to send that data in the requested format in the Accept header, then the server sends the 406 Not Acceptable error.
The 406 error can appear accordingly to your mod_security rule on the server. Mod_security is a security module of Apache web server, usually permitted automatically on all hosting profiles. In case if a site, page or even function violates one of the rules, server can send the 406 error.
How to Prevent
You can turn mod_security off. Also, there is a possibility to disable a specific rule or each domain individually. Thus, if you wish to disable mod_security, go to mod_security using modsec manager plugin in control panel.
Note: There may not be the option of turning mod_security on/off in your cPanel or dedicated servers. In such cases, use command line using SSH or contact tech support to enable/disable this option.
Posted in: Troubleshooting