*** This bug is a duplicate of bug 47838 *** I finally found a solution :
sudo sed -i "s/SystemMenu=false/SystemMenu=true/" /etc/X11/gdm/gdm.conf sudo sed -i "s/SystemMenu=false/SystemMenu=true/" /etc/X11/gdm/gdm.conf-custom -- no shutdown and reboot menu since gdm 2.14.7-0ubuntu1 upgrade https://launchpad.net/bugs/50009 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs