Not sure if this helps but I'm experiencing the same gnome-session error as OP on a Debian 8.6 Jessie (amd64) system (regardless of kernel version, in case that matters) with gnome-session 3.14.0-2.
Not sure if this helps but I'm experiencing the same gnome-session error as OP on a Debian 8.6 Jessie (amd64) system (regardless of kernel version, in case that matters) with gnome-session 3.14.0-2.