I had just finished upgrading, and now, when I restarted the system to complete the installation process, Ubuntu does not start.
The boot menu and GRUB work fine, leading me to the boot menu when I request it. But instead of booting, the system is stuck at a frozen light grey screen bound by a darker grey border. I tried entering recovery mode, but it doesn't work. What am I supposed to do now?
The upgrade process ended, but I remember reading a line which said that there were errors. How should I solve this problem?
By the way, I have NVIDIA drivers installed, and recently I had been experimenting with KVM virtual machines.
EDIT: I tried to follow this tutorial, which was a failed attempt at trying to transfer the GPU to a virtual machine instance that ran on KVM. Do you think I could have messed up something there?