Got same issue after an upgrade from Ubuntu 14.04 to 16.04 and the following actions solved the problem :
sudo pam-auth-update --force sudo vi/etc/pam.d/lightdm
=> add following lines at the end : session required pam_loginuid.so session required pam_systemd.so
sudo reboot
Got same issue after an upgrade from Ubuntu 14.04 to 16.04 and the following actions solved the problem :
sudo pam-auth-update --force pam.d/lightdm
sudo vi/etc/
=> add following lines at the end :
session required pam_loginuid.so
session required pam_systemd.so
sudo reboot