Convert BIOS (Legacy Boot) Proxmox PVE Host (VM) to UEFI Boot

[pugglewuggle]

Is there a tutorial for this anywhere? I see several posts - mostly this one https://forum.proxmox.com/threads/how-to-migrate-from-legacy-grub-to-uefi-boot-systemd-boot.120531/ - about how to do this with a ZFS root file system but nothing for LVM/EXT4 root file system. I cannot get this to work. It seems that GRUB is broken when booting with UEFI and it just crashes back to the UEFI setup. If I change back to BIOS it boots fine. I am running a Proxmox VE Host as a guest on Synology Virtual Machine Manager (extra quorum vote and LXC functions only). I cannot figure out how to switch from BIOS to UEFI boot. Additionally, I have referred to https://pve.proxmox.com/wiki/Host_Bootloader and proxmox-boot-tool returns the following message when proxmox-boot-tool status is run as root:

Re-executing '/usr/sbin/proxmox-boot-tool' in new private mount namespace..
E: /etc/kernel/proxmox-boot-uuids does not exist.

I am on version 9.1.

 

[pugglewuggle]

Anyone?

 

[ovaloffend]

Is there a tutorial for this anywhere? I see several posts - mostly this one https://forum.proxmox.com/threads/how-to-migrate-from-legacy-grub-to-uefi-boot-systemd-boot.120531/ - about how to do this with a ZFS root file system but nothing for LVM/EXT4 root file system. I cannot get this to work. It seems that GRUB is broken when booting with UEFI and it just crashes back to the UEFI setup. If I change back to BIOS it boots fine. I am running a Proxmox VE Host as a guest on Synology Virtual Machine Manager (extra quorum vote and LXC functions only). I cannot figure out how to switch from BIOS to UEFI boot. Additionally, I have referred to https://pve.proxmox.com/wiki/Host_Bootloader doodle baseball and proxmox-boot-tool returns the following message when proxmox-boot-tool status is run as root:

Re-executing '/usr/sbin/proxmox-boot-tool' in new private mount namespace..
E: /etc/kernel/proxmox-boot-uuids does not exist.

I am on version 9.1.

you can’t reliably convert a Proxmox VE system disk from legacy BIOS to UEFI when it’s running as a guest VM the way you describe — especially with ZFS root — and the error you’re seeing is expected.

Key points you can reply with:

• proxmox-boot-tool only applies to bare-metal installs using systemd-boot.
  The error
  E: /etc/kernel/proxmox-boot-uuids does not exist
  means your system is not installed in a UEFI/systemd-boot layout, so there’s nothing to convert.
• GRUB → UEFI migration on ZFS root is not supported in-place on Proxmox. The wiki page you linked explicitly limits supported scenarios, and most successful conversions are for EXT4 + bare metal.
• Since this is a nested Proxmox VE running as a VM on Synology VMM, the clean solution is:
  
  1. Create a new VM set to OVMF (UEFI) from the start
  2. Reinstall Proxmox VE in UEFI mode
  3. Restore configs/VMs from backup (or migrate storage if applicable)
• Switching the VM firmware to UEFI after the fact breaks GRUB, which explains the boot loop you’re seeing.

TL;DR: There’s no supported in-place conversion here. Back up, reinstall Proxmox with UEFI enabled on a new VM, then restore.