I get pretty much the same error with Gantry 3.1.3 when I try to change the template configuration:<br /> <b>Fatal error</b>: Call to a member function isAdmin() on a non-object in <b>/home/jrtcllcc/public_html/pathkeeper/administrator/templates/system/gantry-ajax-admin.php</b> on line <b>17</b><br />
I noticed this on two site using different Rocket Theme templates (Hybrid & Zephyr) when I clicked "Apply." If I click "Save," the changes seem to "take."
For the time being, I rolled back to Gantry 3.1.2.
Cheers!