[ISSUE] No UEFI boot after Proxmox 9 upgrade from legacy boot

[rickythewoof]

Hello everyone! I wanted to share my story so that I hope nobody will have to endure what i had to.
I recently upgraded my Proxmox server from version 8 to 9. Running the command pve8to9I understood that i needed to uninstall systemd-boot and install grub-efi-amd64, and so I did, and continued with my install. This removed my legacy bios boot, and tried to install uefi boot. After the upgrade, the system would no longer boot in UEFI mode, at all. When selecting the UEFI boot option, I would see a brief “Welcome to GRUB” flash and then the system would immediately reboot. Legacy BIOS boot still worked fine, but this was a problem because after a reboot the server would always try to start in UEFI mode and fail.

After investigating, I found that the EFI partition had the stub grub.cfg pointing to a non-existent /grub folder. Even though proxmox-boot-tool refresh and reinstalling grub-efi-amd64 updated the EFI binaries, GRUB could not find the full configuration file with all kernel entries, thus it just rebooted right after the welcome screen, without any sort of issues. The solution was to create the missing /boot/efi/EFI/proxmox/grub/ directory and then rerun proxmox-boot-tool refresh so that grub-install could write grub.cfg correctly.

At this point my suggestion, if applicable, is to check for the folder existence when running pve8to9, or doing so during proxmox-boot-tool

I really hope I saved someone a few hours of their time with this

 

[NewbAdmin]

Thanks for the assist, guy. I'm not sure if it made a difference for me at all, but I took a slightly different route. Just in case, here's what I did:

• Checked lsblk for a /boot/efi mountpoint (I didn't see one)
• Compared with my other 2 hosts and saw that the misbehaving server was also missing an EFI mountpoint in /etc/fstab
• Copied in the missing line in /etc/fstab from one of the known-good servers, replacing the UUID with the one listed in lsblk -f output
• Ran proxmox-boot-tool refresh (again, thanks)

I've got 3 servers. 2 of them upgraded fine. The third one would only boot in legacy mode. Can't win 'em all, I guess.