Over the weekend I upgraded my dual boot ACER A314 laptop from 18.04 LTS to 20.04 LTS, and then 22.04 LTS. The 22.04 LTS installation seemed to work, but on first reboot, failed.
The error messages from attempted recovery mode boot are
- 'Cannot open root device....append or correct "root=" boot option....Kernel panic - unable to mount root fs on unknown block (0,0)'
So far I have, using a Live USB of 22.04:
- created a chroot environment
- updated/regenerated initramfs using 'update-initramfs -u all' for the two kernels that dpkg sees
- installed grub with target x86_efi, followed by install recheck
- updated grub.
All the above gave me a working grub with Ubuntu, Windows and UEFI entries. But the problem persists.
I have also subsequently run the Boot-repair program in basic mode from Live CD - problem not solved.
Both the Ubuntu and EFI partitions have 50% free space. The kernels that dpkg sees are 5.4 versions - I would have expected 5.15 or higher - don't know about this.
How to proceed/fix?
Thanks in advance.
After going down and eliminating many rabbit holes, the clue was in the kernel versions.
I ran Boot-repair, with the "purge kernel" selection checked, within advanced options - grub.
This deleted the old 5.4 kernels and installed a 5.15 kernel.
At the same time, I purged and recreated grub, using the tool option.
Finally, a working Ubuntu 22.04.