No login screen after uninstalling Unity with lightdm

Linux, Ubuntu / March 15, 2021 / ashishpsk / 0

Today out of curiosity I tried installed Unity on Ubuntu 20.04 and after uninstalling it, on rebooting blank screen appeared rather than Ubuntu 20.04 login screen:

The black screen appears because the Ubuntu boot process defaults to tty7, the terminal where the graphical login (lightdm) would normally be running.

To get to a login prompt, you can switch manually to one of the other ttys using Ctrl+Alt+F1

For a permanent fix, edit /etc/grub.d/10_linux as root:

sudo vim /etc/grub.d/10_linux
Find the line that says

        set vt_handoff=vt.handoff=7
and replace it with

        set vt_handoff=vt.handoff=1
To apply the setting, you need to run update-grub as root:

sudo update-grub

This changes the default tty to tty1, where a text login prompt is usually running.

After that you need to set display manager to gdm3 rather than lightdm. Run

sudo dpkg-reconfigure gdm3

If you get the error:
===
gdm.service is not active, cannot reload.
invoke-rc.d: initscript gdm3, action “reload” failed.

Just reboot and you should be running gdm3. The error that you’re receiving just means that gdm3 wasn’t already running, so it couldn’t reload it.

Ubuntu

ashishpsk