Recreate EFI boot partition

Applies to UEFI/GPT

The EFI boot partition and BCD store may be corrupted following a re-order of partiions.  Provided the Windows folder is not currupted the EFI and BCD are easily rebuilt.

The EFI partition is typically 100MB and is best located at the start of the disk

To create a 100MB EFI partition on disk 0

diskpart

select disk 0

create partition efi size=100

format fs=fat32 quick

A drive letter needs to be assigned to the newly created partition

To assign the letter S: to the EFI partition 1 on disk 0

diskpart

select disk 0

select part 1

assign letter=s

exit

To create the BCD and register the c:\Windows operating system

bcdboot c:\Windows -s E:

diskpart

select disk 0

select part 1

remove letter=s

exit

Reboot windows twice.  The first reboot will probably fail.