I am running Ubuntu 16.04 on VirtualBox 6.0. The hosting system is Windows 10.
Before everything started to fail, I've had installed VirtualBox 5.2.2. After that, there appeared a dialog inside of Ubuntu, that said, that there are updates of some applications and the kernel. I have updated those programs through that dialog. Then I have upgraded to VirtualBox 6.0.
After I restarted everything, Ubuntu started to show only the desktop wallpaper. Then I opened the terminal with Ctrl + Alt + F1. I typed in
sudo service lightdm restart, to restart
lightdm. After pressing enter, the ubuntu appeared for about half of a minute and then this message came up:
Message after lightdm restart
I typed in
systemctl status lightdm.service to see why it failed, then this shows up:
Failed to start Light Display Manager.
journalctl -u lightdm:
journalctl -u lightdm
And now I do not know how to solve this error. It would be very helpful if somebody could help me with this problem.