Grub issue after upgrading from Core to Scale

[markds]

Took the plunge and attempted to upgrade one of my Truenas Core 12-U8 boxes to Truenas Scale 22.02.0.1 via the manual update method. Everything worked well, but after installing the system boots to a grub error.
-------------------------------
GRUB Loading..
Welcome to GRUB!

error: unknown filesystem.
Entering rescue mode...
grub rescue>
-------------------------------

From the rescue shell I can "ls" and see my boot device as well my 4 drives in my pool.
However I can not do an ls of any of the partitions. ie "ls (hd0,gpt1)"
I am unable to run "lsmod" (thought grubs zfs module might not have been loaded), returns unknown command
I am unable to run "search" as it also returns unknown command

Any help would be greatly appreciated.

 

[markds]

I should also add that I am able to run:"insmod zfs" without an error but unable to run "insmod boot" or "insmod normal" and hence unable to boot the system...

 

[markds]

Having tried all options I can think of in the grub rescue shell, I decided to download and use the iso to reattempt the upgrade again. Unfortunately after the upgrade process completed, the first reboot leads to the same grub rescue shell...

 

[markds]

for anyone else who had the same issue, I ended up overwriting my previous install with a new scale install and restoring a backup of core to the new install. now everything is working..