I had Windows 8 installed, and tried to install Xubuntu in another HDD on my desktop. After installation, I could only boot into Xubuntu, and never got into the OS selection menu in GRUB. So I ran Boot Repair in order to fix the boot problems.
The boot process got fixed, now it does boot into GRUB, where I have two Windows entries, but none of them actually work, I get the error:
error: no such device: 1CA0-4000 error: file 'EFI/Microsoft/Boot/bkpbootmgfw.efi' not found
I've tried to run the Windows 8 installation again, and chose Automatic Repair, but it was not able to correct the problem. So I guess the EFI files in the windows EFI boot partition of the 1st disk got deleted/chaged. How do I get them back/fix the windows bootloader?
I'm doing all of this with UEFI boot, both in the OS installed on the disks, and the installation media (booting from a USB flash drive).