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

  • Your question is a bit confusing and very unclear. Perhaps you can edit it to clear some things up: "installed portable Ubuntu 19.04 to an external HDD" -- what are you referring to when you say "portable Ubuntu"? Are you trying to set up a dual-boot configuration? What answers did you find that say "it's not possible" and what exactly is "it" that you are trying to accomplish: Are you unable to boot at all? – Nmath Jul 6 at 17:25
  • 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. – GabrielaGarcia Jul 6 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 at 20:00

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.

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