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How to repair Windows 8 and Windows 10 bootloader on UEFI system

Repair UEFI bootloader-Windows8-advanced option-command-prompt

In certain situations like installing dual boot with second OS, or cloning Windows 8 (or Windows 8.1) installed with UEFI mode,  corruption of the Windows 8 bootloader can occur.
It can be caused by some reasones like failure recovering os somethnig like that. If the bootloader in Windows 8 installed on UEFI system is corupted, it’s not posible to start the system. Blue screen apear with following error:
The boot configuration data for your PC is missing or contains errors.
File :\EFI\Microsoft\Boot\BCD
Error Code: 0xc000000f

or this error:
The boot configuration data for your PC is missing or contains errors.
File: \windows\system32\winload.efi

Boot Windows 8 UEFI BCD error code

This error can impose corruption or total removal of WIndows 8 boot configuration data (BCD). BCD loader can’t be recovered using bcdedit. Using this tool,will appear error like this:

The boot configuration data store could not be found.
The requested system device cannot be found

The point is that the BCD loader configuration in Windows 8 installed in UEFI mode is stored on a separate hidden EFI volume ( 100 MB in size on FAT32 file system, or even 500 MB after upgrade to Windows 10), and BCDEdit can not see this hidden volume and, therefore, can’t manage loader configuration on it.

To recover the loader configuration ( BCD), you have to boot from original installation Windows 8 DVD (or recovery disk or EFI bootable USB flash drive), DVD will do the job.
Boot from DVD, choose System Restore-Troubleshoot-Command Prompt or press Shift+F10

Windows 8 Boot DVD recovery advanced options

Start disk part, then Display the list of disk in the system:

>diskpart

>list disk

Select the disk with Windows 8 installed ( if there is one disk in the system, it will be with zero index on it ):

>sel disk 0

Display the list of volumes in the system on that disk:

> list vol

disk part_list disk_list volume

In this example you can see that EFI volume ( can be find by its size of 100 MB FAT32, of if you upgrade Windows 8 to Windows 10, will be create another EFI  hidden volume with size of 500 MB and FAT32 file system) has the index volume 7, and the Windows 8 is installed on volume 5 with drive letter C:

Assign any unused disk letter to the EFI volume:

>select volume 7

>assign letter W:

Then close diskpart:

>exit

Now go to the bootloader directory in the hidden volume and recreate the boot sector on the boot partition:

> cd /d W:\efi\microsoft\boot\

>bootrec /fixboot

Delete the current BCD configuration file , you can do this by renaming it and save the older configuration as backup.

>ren BCD BCDoriginal.bac

With bcdboot.exe create BCD store again by copying the boot files from the system directory:

>bcdboot c:\windows /l en-US /s W: /f ALL

Explanation: C:\Windows is the path to the Windows 8 installation directory, /f ALL- boot files have to be copied including those for UEFI and BIOS computers ( ability to boot in EFI and BIOS systems)
/l en-US is system locale, bu default English (USA) is used.

NOTE: I notice that in some circumstances if you want to solve this problem you need to manually reconfigure drive letters while you are still in diskpart tool, you need to change drive letter on system partition from your original Windows installation ( if you remember it ) with same drive letter in disk part. If this is NOT the case, you need to change drive letters to set your system partition to be the same drive letter  with disk part tool ( this mean little rearrange of drive letters – to set drive letter on system partition to be the same as it has been on your windows installation). Than you repeat same procedure again. It work for me sometimes, when I had those kind of issues.

Now you have to restart computer. In the list of bootable devices here will appear Windows Boot Manager where you can choose your OS to start. Hope this article will help when you find yourself in this kind of situation like I do.

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