Repairing Windows Boot Loader (BCD)
In this article we will find out how to repair Windows 10 boot loader on a computer operating in UEFI mode. Damage to Windows 10 boot loader may result from installation of another OS ОС (in Dual Boot configurations), incorrect actions of an “expert” when recovering the system after a failure and from a number of other reasons.
The signs to suggest damaged boot loader of Windows 10 installed in UEFI mode can include the system’s boot failure and emergence of a new BSOD with an error:
The boot configuration data for your PC is missing or contains errors.
File :\EFI\Microsoft\Boot\BCD
Error code: 0xc000000f
All these may indicate damage or even complete removal of Windows 10 boot loader configuration — Boot Configuration Data (BCD). When trying to execute command bcdedit the system shows an error:
The boot configuration data store could not be found. The requested system device cannot be found.
The matter is that Windows 10 BCD loader configuration installed in UEFI mode is stored in a separate hidden EFI partition (with the volume of 100 Mb and having FAT32 file system), which the utility bcdedit cannot recognize and therefore it cannot manage the configuration of the boot loader stored there. Now, in order to restore the boot loader (BCD) configuration, we should boot from an authentic Windows 10 installation DVD (or from a recovery disk or a specially created bootable flash drive) and launch the command prompt:
Launch diskpart:
diskpart
List the disks available in the system:
list disk
Select the disk where Windows 10 is installed (if there is only one hard disk drive in the system, it will have a zero index):
sel disk 0
List the volumes available in the system:
list vol
In our example, we can see that EFI partition (you can see it from the size of 100 Mb and FAT32 file system) has the index “volume 1,” and the boot partition containing installed Windows 10 is marked as “volume 3.”
Let us assign a random disk letter to the hidden EFI partition:
select volume 1
assign letter M:
Finish work with diskpart:
exit
Go to the directory containing the boot loader in a hidden partition
cd /d m:\efi\microsoft\boot\
Create again the boot sector: in the boot partition
bootrec /fixboot
Delete the current file with BCD configuration by renaming it (save the old configuration as a backup copy):
ren BCD BCD.bak
With the help of bcdboot.exe utility, create again the BCD storage by copying boot environment files from the system directory:
bcdboot C:\Windows /l en-us /s M: /f ALL
where C:\Windows is the path to the directory where Windows 10 is installed.
/f ALL – it means that it is necessary to copy boot environment files, including files for computers with UEFI or BIOS (it suggests theoretical opportunity to boot in EFI and BIOS systems)
/l en-us — system locale type. By default, en-us is used — English (USA).
The only thing left to do is to restart your computer, after that the item Windows Boot Manager should appear when selecting boot devices from the list where you select the OS you want to load.
It often happens that for some reason become impossible to recover operating system, resulting in damage or even complete removal of the boot loader configuration (BCD). You may not have the original installation disc or a specially prepared a bootable USB drive. As a result, you get a computer with broken operating system.
You need to reinstall your OS with prior formatting the disk.
If you need to recover data from such computer there is a solution – data recovery software.
Immediately after reinstalling the operating system, install data recovery program and scan the disk. Just remember that recovered files in this case better save to another storage, otherwise you may overwrite recoverable data.
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Thanks for not skipping any steps or assuming we know XYZ. Your solution worked like a charm. Thanks!
Thank you for the article. In my humble opinion, the problem you have described is very often even for users of Windows 10 Anniversary Edition. As for me, I helped my girlfriend to solve such problem yesterday, because she is not an advanced PC user. This text is able to be helpful for such people.
I've been always using Windows 8 at my computer and about two weeks ago I decided to try Windows 10, so I don't understand it really well yet. Still don't know the reason but yesterday my boot loader suddenly failed. This article is really useful, because only with the help of it I managed to repair the boot loader. But I have one question, I didn't get how to delete the file with BCD configuration by renaming it? I've just created another one and it worked...
Is it recommended to attempt Boot Loader repair on your own, or should you seek professional assistance?
It is not recommended to attempt Boot Loader repair on your own, as it can be difficult and complex. It is best to seek professional assistance in order to ensure the repair is done correctly and efficiently.
How can you prevent Boot Loader failure in the future?
What is a bootable USB drive, and how can it be used to repair the Boot Loader?
A bootable USB drive is a USB flash drive that contains an operating system or other software that can be used to boot a computer. It can be used to repair the Boot Loader by allowing you to access the system files and replace or repair any corrupted or missing files. This can be done by using a bootable USB drive to boot into a live operating system, such as Linux, and then using the appropriate tools to repair the Boot Loader.
Can the Boot Loader be repaired without the Windows installation media or a third-party tool?
No, the Boot Loader cannot be repaired without the Windows installation media or a third-party tool. The Windows installation media is necessary to repair the Boot Loader, as it contains the necessary files and instructions needed to repair the Boot Loader. Third-party tools can also be used to repair the Boot Loader, but they are not necessary.
What is the BCDEdit tool, and how can it be used to repair the Boot Loader?
BCDEdit is a command-line tool used to edit the Windows Boot Configuration Data (BCD) store. It can be used to repair the Boot Loader by allowing users to create, delete, and modify entries in the BCD store. It can also be used to set the default operating system, configure boot loader settings, and add and remove boot menu options.
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