I installed Ubuntu 19.04 to an external HDD,in UEFI using a laptop.

I then tried booting it through my desktop (BIOS only, Windows 10), but an error popped up, about missing normal.mod file, prompting grub rescue>. I figured out the normal.mod is in some x86_64-efi inside /boot/grub/ basically UEFI installed. But BIOS is trying to find it in /boot/grub/i386-pc.

Can i go to boot/grub and make copy of the x86_64-efi folder and name it i386-pc? Is that possible or do I have to format the disk or install in BIOS? Can anyone suggest a lossless conversion method for GPT to MBR? Thank You

  • And you don't need to convert to MBR. Unlike Windows, Ubuntu can be installed in a GPT In Legacy mode, it just needs an unformatted bios_grub partition at the beginning of the drive.
    – user880592
    Jul 6, 2019 at 19:51
  • 1
    No guarantees on conversion, but this usually works. Converting to or from GPT - must have good backups. rodsbooks.com/gdisk/mbr2gpt.html Note that Windows only boots in UEFI mode from gpt and BIOS mode from UEFI. And Ubuntu needs an ESP if UEFI boot or a bios_grub if BIOS on gpt drives. I used to always but both as first two partitions on every new or repartitioned/reformatted drive and only used gpt.
    – oldfred
    Jul 6, 2019 at 20:00

1 Answer 1


You may try this steps:

  1. Install VirtualBox (or any other virtual machine emulator) onto your laptop.
  2. Create virtual machine without UEFI in your case.
  3. Mount to it ubuntu.iso and your physical external HDD via USB as a single boot drive.
  4. Install Ubuntu.
  5. Stop virtual machine and replug your HDD to desktop.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy