"Failed to Start Image Provided by ZFS" after using upgrade utility from 11.3 to 12

[mikehsg]

Title pretty much says it. Went in to the system, hit the "Update" utility. Said that 12 was stable, so changed the train to 12. Downloaded. Looked like it was going fine - dashboard was running progress, life seems on track. System hit 100%, rebooted, nada. Hard and soft rebooted the machine a few times. Looks like it sees my media pool (aptly named "mediapool") but it won't boot and I can't launch the GUI from my network.

Help?

Thanks!