Seltox wrote:It's MBR.
Although, after some thinking, and looking at bank balances, I decided to purchase a second SSD to run Linux off, and am going to do a full reinstallation of my system. This isn't so much a reaction to the bootloader problem I have, but rather something I wanted to do, and fixing the bootloader issue is just a happy side effect.
In that case, the easiest solution is to ensure that you run the Mint installer in BIOS mode rather than in EFI mode. (I'm guessing it's currently booting in EFI mode since the error message about an EFI file path strongly suggests an EFI-mode boot loader installation.) You can check the boot mode of the installer by dropping to a shell and checking for a directory called /sys/firmware/efi. If it's present, you've booted in EFI mode. If it's absent, you've probably
booted in BIOS mode, although there are ways for it to be absent while you're actually booted in EFI mode. If this is the case, typing "sudo modprobe efivars" will usually make the directory appear, so try that and check again. If you boot in EFI mode, reboot, use your firmware's boot manager, and try to find a boot option for the installation medium that does not
include the string "EFI" or "UEFI" in its description.