XF 2.1 Problem with node permissions

[boeing747]

Hello,

When I want to set a new permission for a node it shows to me below error:

Oops! We ran into some problems. Please try again later. More error details may be in the browser console.

Also I checked browser console:

406 Not Acceptable
Not Acceptable
An appropriate representation of the requested resource /admin.php could not be found on this server.

 

[Paul B]

That is most likely going to be some sort of security mechanism on the server, such as mod_sec.

Your host will be able to assist.