GRUB: unknown filesystem on ZFS-based Proxmox

Proxmox team has released a fix for this bug.

Recently I experienced a very frustrating bug with one of the hosts in my Proxmox cluster. It was not the first time I experienced this bug, previously I was not aware of any fix and had to re-install the system if this occurred. Fortunately there is now a fix!

What would happen is you would update your Proxmox installation and a zpool upgrade on the ‘rpool’ occurs, then you reboot, and find that your system is unbootable when you see the following error:

Error: unknown filesystem.
grub rescue>

This would occur if the following points are true:

  • System installed using Proxmox VE ISO 6.3 or earlier
  • System uses GRUB legacy BIOS boot to boot
  • System is using ZFS as the root filesystem

Fortunately there is an official fix now!

Notes

updatedupdated2021-08-292021-08-29
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