No boot loader is installed in the MBR of /dev/sda. Is that some pain to a only Win8.1 system?

After I made a dual-boot (Win8.1/Ubuntu 14.04) I wanted to remove Ubuntu. I am a really newbie guy at this.

First I deallocated the Ubuntu partitions at Win8.1 and joined them into the Win8.1 OS partition. I wanted to leave my computer as it was before, when during BIOS, pressing F12 lead me to system settings and F11 lead me to boot options. But grub was already there. I used a flash drive Ubuntu image to run boot-repair. After this, I created this log. Is everything alright?

What does "No boot loader is installed in the MBR of /dev/sda." means?

In general, you need to look at the whole context. From your Boot Repair output, you've got:

No boot loader is installed in the MBR of /dev/sda.

You also say you had Windows 8.1 installed. The vast majority of computers pre-installed with Windows 8 and 8.1 boot in EFI/UEFI mode, but this can be confirmed by:

    Boot files:        /EFI/Boot/bootx64.efi /EFI/ubuntu/MokManager.efi 
                       /EFI/ubuntu/grubx64.efi /EFI/ubuntu/shimx64.efi 
                       /EFI/Microsoft/Boot/bootmgfw.efi 

                       /EFI/Microsoft/Boot/bootmgr.efi 
                       /EFI/Microsoft/Boot/memtest.efi

...and:

/dev/sda1                   1 1,953,525,167 1,953,525,167  ee GPT


GUID Partition Table detected.

In other words, this is a GUID Partition Table (GPT) disk with Windows EFI boot loader files (EFI/Microsoft/Boot/bootmgfw.efi) on the EFI System Partition (ESP). Such computers do not normally have BIOS-mode boot loaders installed in the boot sector of the first disk, so the No boot loader is installed in the MBR of /dev/sda message is uninformative.

Two other facts are important:

• You've got Ubuntu boot loaders on the ESP -- all the files under EFI/ubuntu in the Boot files: list.


• Your EFI boot order is shown by the efibootmgr output, and it shows the Windows boot loader as being first in priority.

The first of those issues means that GRUB could in principle be launched in the future. If you want to completely remove Ubuntu from the computer, you must delete those files. This is likely overkill, though, and there's always a risk of a slip-up, so I don't really recommend it unless GRUB launches when you don't want it to. The second point means that GRUB shouldn't be launched by default. The computer should boot directly to Windows when you reboot.

There is one caveat, though: Boot Repair sometimes renames the Windows boot loader and puts a copy of GRUB in its place. If you've chosen the option to do this from the Boot Repair Advanced menu, the computer is likely to boot to GRUB when you reboot. If that happens, you should launch Boot Repair again, open the Advanced menu, select the option to restore boot loader backups, and run a fresh repair.

What any given function key does is very much a firmware-specific thing. Ordinarily, I'd say that the function keys should do the same thing they've always done; but I've heard of bugs that cause EFIs to start ignoring function keys for no apparent reason. (Or maybe their users have inadvertently changed an option and don't know how to undo that change.) Sometimes resetting all the firmware options or re-flashing the firmware fixes things.