booting to emergency mode after 20.04.5 (focal) to 22.04 (jammy) upgrade

Back in 2020, I installed 20.04 using the openZFS on root option provided in the Ubuntu installer. Now (Oct 2022) I ran:

sudo do-release-upgrade

and it completed and rebooted but GRUB menu still shows 20.04 and ends up in emergency mode. Clearly something failed. Please help me find out why/how the upgrade broke the system and how I can fix it!

Screenshots:

• emergency mode
• old snapshot options I could revert to
• zfs modules seem to be loading..
• but then this happens
• and this
• some of the journalctl -xb output
• more

I can get more if there is something I should look for in particular that would help you help me.

Also, as a last resort, I was thinking I could revert to a pre-upgrade snapshot but it looks like they are all 2+ years old. So the automatic snapshots stopped working silently at some point.

This is on a Thinkpad T410 with BIOS boot (not UEFI).

Can I adapt one of these instructions to my scenario?: reddit askubuntu tecmint

This is the current disk/partition layout:

sda disk 931.5G Samsung SSD 860 QVO 1TB (just under half full)
sda1 part 512M vfat (ESP pri part)
sda2 part 1K (extended)
sda5 part 2G zfs_member (bpool) sda6 part 927G zfs_member (rpool)

This is the output from running the boot-repair tool: (it seems to suggest changing bios to UEFI boot mode which I am trying now.

This Ask Ubuntu Question could be the same issue: (no solution!)

• Ubuntu 20.04 with root on ZFS errors after 'apt dist-upgrade'

This problem seems common: