Windows 10

Windows 10 Repair UEFI Boot Partition

Start a command prompt and run:

diskpart

In 'diskpart' run

list disk

Select the disk with Windows installed (if there is one hard disk in the system, its index should be 0):
sel disk 0

Display the list of partitions and volumes on the disk:
list partition
list volume

Usually the UEFI partition will be the hidden 100MB FAT32 partition

Then you can assign a letter to the volume by running:

select volume <volume number that contains UEFI partition>

assign letter k:

You can use the 'attrib' command to remove hidden flags from the BCD file.

I.E. attrib -s -r -h k:\EFI\Microsoft\Boot\BCD

Then rename the file:

ren k:\EFI\Microsoft\Boot\BCD BCD.bak

Then you can recreate the BCD file by running the following:

bcdboot C:\Windows /l en-us /s k: /f ALL

The following are some flags and options to be aware of:

C:\Windows – is the path to the directory with Windows 10 installed;

/f ALL – means that you want to copy the Windows Boot Environment files, including those for UEFI and BIOS computers (potential ability to boot in UEFI and BIOS systems). To copy only the EFI bootloader, use the /f UEFI command;

/l en-us — is a type of the system locale. By default, en-us – English (USA) is used;

/c – this is a new BCDBoot option in Windows 10 that allows you to overwrite existing boot records (including debugsettings). Use this option to ignore old boot settings and create a clean BCD configuration;

/v – used to enable BCDBoot verbose output.