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

rickythewoof

New Member
Sep 21, 2025
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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
 
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