Upgrading Debian 10 to Debian 11 Bullseye, no graphical user interface starts!

When I upgraded to Debian 11 Bullseye (from Debian 10 Buster) on my laptop, I ended up after reboot on a black console screen. After a few seconds of disarray, I assumed the new configuration was lacking a proper Display Manager. And indeed, for a reason I ignore, the display manager was somehow removed when executing "apt autoremove" after the upgrade. I don't know why it was flagged as a useless package.

To fix this, I just re-installed a display manager, for example lightdm.

apt install lightdm

Then reboot et everything was back to normal! Enjoy Debian 11 Bullseye and thank you to all those making it possible!