The other day, I had the great idea of updating my laptop’s Ubuntu 9.10 to Lucid Lynx (10.04) beta. If you also feel like doing this, press ALT+F2 and type
This will show the update manager with an option to upgrade. However, after doing this I never got further than the (new) xsplash screen.
So, time to start problem solving. I started with picking the recovery mode option in GRUB and found out that there was a problem with mounting of internal hard drives. To solve it, I grabbed my trustworthy USB stick with Slax on it and booted from it. Once booted into it, it was simply a matter of opening
which states how things should be mounted and finding out what was wrong with it. Turns out the update had messed with its contents and ruined a line I had added myself. So I commented it out quickly, rebooted into Ubuntu and tadaaa booting behaved as it should.