Rich Dougherty ⬦ rd.nz

Upgrade to Ubuntu 20.04 from 19.10

Usually I upgrade from one partition to another using a semi-manual process. This time that didn’t work (the ISO didn’t load) so I tried the automatic upgrade process using do-release-upgrade.

There was a major issue with this upgrade, with loading my root filesystem. The error message was:

Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(0,0)

To make this work I needed to load the previous kernel in safe mode, fix up the packages (which I think rebuilds the kernel init image?) and then reboot in the new kernel. This was explained in this Ask Ubuntu answer from krangerich.

  1. Hold SHIFT during boot to get GRUB menu (it will appear after the first failed boot automatically, though)
  2. Choose “Advanced options for Ubuntu”
  3. Choose the older kernel in recovery mode (Linux 5.3.0-51-generic (recovery mode))
  4. In the Recovery Menu, choose “dpkg - Repair broken packages”
  5. After repair, reboot. Hold SHIFT again
  6. Now choose “Advanced options for Ubuntu”/older Kernel again, this time WITHOUT recovery mode
  7. System should now properly boot with GUI. uname -a will show the old kernel 5.3.0
  8. Simply reboot again
  9. System should now magically boot with GUI and the new 5.4.0 Kernel