Under Ubuntu root User Login

1. Log in with other users

Open terminal, input: sudo gedit/usr/share/lightdm/lightdm.conf.d/50-ubuntu.conf

Or: sudo vim/etc/lightdm/lightdm.conf

2. Add the following content

[Seatdefaults]

Greeter-session=unity-greeter

User-session=ubuntu

Greeter-show-manual-login=true

Allow-guest=false

3. Set the root user password

sudo passwd root

4, then you can log in with the root, but when logged in, the following error will appear:

Error found when Loading/root/.profile

Stdin:is not a TTY

Workaround:

in the terminal with Command gedit/root/.profile, open the file and find "Mesg n", change it to "Tty-s &&mesg n"

5. Restart reboot

Under Ubuntu root User Login