I was able to to do it on 17.04, but i guess the display manager has changed
I know it is not recommended. But it eases a lot of things for me.
Ask Ubuntu is a question and answer site for Ubuntu users and developers. It only takes a minute to sign up.Sign up to join this community
This link points it out for Debian, but instead of
daemon.conf just edit
custom.conf. Everything else is the same.
In a nutshell, first run
sudo vim /etc/gdm3/custom.conf
AllowRoot=true so that it looks like
Save and exit. Then run
sudo vim /etc/pam.d/gdm-password
Within this file you have comment out the line containing
auth required pam_succeed_if.so user != root quiet_success
so that it looks like this
#auth required pam_succeed_if.so user != root quiet_success
Save the file and exit and reboot.