Hi James
Happened to me too, on my Home Server I set up 3 weeks ago. No Migration, fresh install. The process is often reffered to as “sh*t happens!”. 
I actually wiped and reinstalled the whole cabodle - for the reasons I was documenting the process and I wanted a 100% clean install and docu!
As everything was on Proxmox as a VM, this was quite fast.
The docu is here, btw.:
My 2 cents
Andy