How can I recover Ubuntu after a failed upgrade that leaves a black screen?

[JonathanT]

I just tried to update my Ubuntu install from 22.04 to 24.04 using the command line, but the process failed halfway through. Now my system boots to a black screen with a blinking cursor. I can get to a tty terminal, but I’m not sure what to do next to recover my installation without losing my home folder.

[Timothy78]

That sounds rough. Since you can reach a tty, start by fixing the upgrade first. Run sudo dpkg --configure -a then sudo apt-get -f install. After that run sudo apt-get update and sudo apt-get upgrade. If the upgrade completes, reboot and see if the system comes up. If the boot still stalls with a black screen, try reinstalling the desktop meta package: sudo apt-get install --reinstall ubuntu-desktop. If you suspect the kernel, you can install a known-good one: sudo apt-get install --reinstall linux-image-generic linux-headers-generic. If you’re worried about data, consider backing up from the live USB before making more moves.

[Jack_W]

Grub menu path: reboot, hold Shift to access the menu, choose Advanced options for Ubuntu, then Recovery mode. Enable networking if possible, drop to the root shell, remount the filesystem rw, and run dpkg --configure -a and apt-get -f install. Then apt-get update and reboot. If that doesn't help, boot from a live USB and chroot to repair packages. The goal is to repair without wiping data.

[BenjaminJR]

I upgraded once and ended up with a black screen; I tried a few things and ended up doing a clean reinstall, but I kept a copy of my data on a separate disk and it saved me. If you want to avoid reinstall, you could try reinstalling the desktop stack or the login manager: sudo apt-get install --reinstall gdm3 or lightdm, then update-grub. I can't promise it will fix it.

[AbigailYJ]

Could the real issue be the login manager not starting instead of the upgrade failing?