Comment 21 for bug 2051999

Wahoo! Found the magic combination.

chrooted into the broken jammy system.

Add a Noble sources list.

Add the ppa. Edit the added /etc/apt/sources.list.d/ubuntu-uefi-team-ubuntu-build-jammy.list's active line to:
>>>
deb [trusted=yes] https://ppa.launchpadcontent.net/ubuntu-uefi-team/build/ubuntu/ noble main
>>>
Update the apt cache

Install grub-efi-amd64 & grub-efi-amd64-signed from the ppa.

Reconfigure Grub2 and update the initramfs images.

Change the sources list back to the original jammy sources.list

There were still existing snapshots there.

Exit the chroot. Umount the mounts. Export the pools. Reboot.

Booted fine.

Fixed. Successful. Booting from Grub2 2.12.

Writing up the work-around to fix it. I can post it on my ZFS -Fixes/Work-Arounds GitHub Repo, and on the htread in the Forum on this problem...Or I can post it here, and refer to this bug report again.

Maybe here is best. That way it is a known work-around for broken affected systems, until we can figure out the next step.

The next step would be, how do we get Grub2 2.12 into Jammy through the updates channel? I would say it first needs to go to jammy proposed, then tested that it works through an update process.

Then respin the installer ISO or include it in the next point release.. Since there is a fix, we don't need to create new victims.

Just thinking out loud.