The error is in policykit-1-gnome 0.105-4
/etc/xdg/autostart/polkit-gnome-authentication-agent-1.desktop refer to Exec=/usr/lib/policykit-1-gnome/polkit-gnome-authentication-agent-1 but it don't exist so it is not started ! The exec is now at/usr/lib/x86_64-linux-gnu/polkit-gnome-authentication-agent-1 I modified /etc/xdg/autostart/polkit-gnome-authentication-agent-1.desktop to set up Exec=/usr/lib/x86_64-linux-gnu/polkit-gnome-authentication-agent-1
