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

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GrehgyHils

New Member
Feb 1, 2023
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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?
 
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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
 
So I have been at this for hours on a new r740 with h740p HW raid 10. I just did identical hardware last week and many other installs zfs and hw raid. I finally saw in another post to check the parition and clear the efi. Finally I booted to gparted live cd and manually cleared out the 3 partitions. Now it just installed without any issues. First time I have had this issue before but hopefully this will help others.
 
GrehgyHils said:
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
Click to expand...
You legend.... This was my issue as well and it fixed it. Thank you!
 
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