Installation Failing: "Failed to prepare EFI boot using Grub"

[GrehgyHils]

Hey all! I'm looking at trying out Proxmox on an old T420 Thinkpad laptop I have lying around. I created a bootable USB of the latest version (7.3-1) of Proxmox and filled out the installation wizard. I ended up getting to the end, at 99% complete, and am greeted with this message:

> Installation failed!
> Proxmox VE could not be installed
> bootloader setup errors:
> - failed to prepare EFI boot using Grub on '/dev/sda2': unable to install the EFI boot loader on '/dev/sda'

I've found a few other people's threads on the internet with this issue, and have not been able to find a solution. I've poked around in my BIOS, and have not found anything that jumped out at me. I've tried installing a few times as well.

Does anyone have any advice?

 

[GrehgyHils]

This was resolved thanks to the Proxcord discord:

https://forum.proxmox.com/threads/proxmox-7-0-failed-to-prepare-efi.95466/ Try this

> Hi Ivanov thanks for you reply
>
> i found the solution for my issue
>
> turns out you just have to make sure the usb flash is the only boot opion that the bios has to boot dont ask my why
> when there is another option even if its last in the boot order it will give you the error
> i think it has to do with the system trying to mount only the /dev/sda no other letters etc.. not sure tho
>
> so on poweredge bios you just have to uncheck all UEFI devices and check only the iso flash driver
>
> regarding the raid so as far as i investigated proxmox will not recognize my drives that are connected to my hardware raid controller without being > configured in a form of raid .. i did not found a solution for that my raid card is the dell perc h710p mini
>
> thanks