How is it that I cannot find/start my Qubes OS after installing it successfully on an external drive?

[disp6252]

Read this:

Weird boot issue

The EFI entries are stored in UEFI NVRAM on your motherboard and when you boot your PC without the drive that contains your EFI partition and the UEFI can’t locate the EFI entry then it’ll just remove this entry. So you can’t boot from removable media using the standard way and for this case you’ll have to use default/fallback boot path: Tip: If you use the option --removable then GRUB will be installed to esp/EFI/BOOT/BOOTX64.EFI (or esp/EFI/BOOT/BOOTIA32.EFI for the i386-efi target) and you…

Weird boot issue

My bad, it should be grub.cfg instead of grubx64.cfg. Full steps from the beginning: Copy files from /boot/efi/EFI/qubes/ to /boot/efi/EFI/BOOT/: sudo cp -r /boot/efi/EFI/qubes/* /boot/efi/EFI/BOOT/. Change filenames grubx64.efi → BOOTX64.efi and grub.cfg → BOOTX64.cfg: sudo mv /boot/efi/EFI/BOOT/grubx64.efi /boot/efi/EFI/BOOT/BOOTX64.efi sudo mv /boot/efi/EFI/BOOT/grub.cfg /boot/efi/EFI/BOOT/BOOTX64.cfg This should be run from dom0 in Qubes OS.