Cannot boot from external drive using Grub

@Soapie hi and welcome to the forum :+1:

  1. When you want to boot from an external drive, that external drive also has to have an $ESP partition the UEFI-BIOS needs to be able to read.
    Otherwise the UEFI-boot entries pointing to the external drive will be silently removed on reboots…

    • This is as far as i know intended behavior of the UEFI-BIOS’s for removable-drives.
    • If the removable drive has it’s own $ESP which instructs the UEFI-BIOS to create those entries again, they will be re-added.
  2. To make grub use the external harddisk to load it’s needed configuration it is using a grub.cfg file inside the same directory as grubx64.efi inside the $ESP of the respective drive the UEFI-BIOS used to execute grub.

So to assist further you need to start providing some info about your setup…

  • lsblk -fa
  • efibootmgr --verbose
  • Contents of grub.cfg inside the $EFI of both hard-disks if you have both.
    Else only the one your computer has and mention it’s location.
    (This is not the same file as /boot/grub/grub.cfg !)

Yes bootloaders can be a pain :wink: