2.4.5p1 upgrade to 2.5.2 in HyperV zfs error 2

[drchanas]

I have 4 pfSense VMs runing on HyperV. Default setup on zfs running 2.4.5p1.
I try to upgrade to 2.5.2 either from console or UI. Without any apparent error in first reboot I get this:

Mount from zfs:zroot/ROOT/default failed with error 2: unknown file system.

How can I proceed?

[drchanas]

Any ideas? Is it just trying to mount too early? Is there a way to delay it? Should I just skip ZFS and go UFS to be certain from now on?

[bmeeks]

Although the Redmine Ticket seems to show this fixed back in 2.5.1, your problem seems eerily similar to this one: https://redmine.pfsense.org/issues/11483. Might be something weird going on with the way Hyper-V is presenting the virtual disks ???