Can't boot after upgrade

[dsi]

I'm facing exactly the same issue with HP server. Any idea how to boot up (at least)
All the VMs are stored as ZFS dataset on the same pool, so no way to reinstall PVE(((

I did a fresh reinstall of PVE on a separate disk and migrated the VMs. I kept the former zfs-pool as storage.

With respect to your question see post #2 of this threat: https://forum.proxmox.com/threads/cant-boot-after-upgrade.32655/#post-160924