My scenario: Ubuntu 14.04 Tried to disable the Guest Session by editing the /etc/lightdm/lightdm.conf with following value. allow-guest=false The lightdm.conf was empty before edit, somehow by writing that caused the screen blank after logged out and wasn't able to login. So I reboot into recovery mode, and rewrite the lightdm.conf as following: mount -o rw,remount … Teruskan membaca Disable Guest Session account