I decided to upgrade one of my older desktop machines from a perfectly nice, working 8.04 version of Ubuntu to 8.10. The upgrade went quite slowly, downloading all the bits and bobs seemed to take an age, but the upgrade did eventually start to run.
I checked on the PC a while later, and it seemed to have gone to sleep, which i thought was odd, so I rebooted it.
After the grub menu, I got :
[1.204117] Kernel panic – not syncing: VFS: unable to mount root fs on unknown-block (0,0)
I thought I was going to be in for the “big reinstall”, and hoped that there wasn’t any data that I was going to lose.
I found a solution though ! I was able to boot into one of the older kernels, and ran the following :-
sudo dpkg –configure -a
That churned away for about 30 minutes, doing TONS of stuff, and finished. A reboot later, and all was working well.
I sort of got the idea of what to do from this post (http://ubuntu-utah.ubuntuforums.org/showthread.php?t=961695)