The boot configuration data store could not be opened. The volume for a file has been externally altered so that the opened file is no longer valid.

mario mario 1 Reputation point

Hello to everyone.

At the beginning I'd installed windows 10 with the legacy BIOS-MBR boot mode,but since I needed a Windows 10 installation that was able to boot using the EFI partition style,I have converted the partition scheme from MBR to EFI with a tool and after this operation I have reinstalled Windows 10 from an old backup. This backup comes from the old BIOS/MBR installation of Windows 10. When I tried to boot Windows,I realized that it was not able to do that (no error message.but blinking cursor). because the EFI partition didn't exist. So,I have created a new FAT32 partition and I have repaired the EFI partition following this guide :

How to Restore Deleted EFI System Partition in Windows 10? | Windows OS Hub

it worked,infact I can use Windows 10 again,but only partially. Infact,since I need to put the "TESTSIGNING ON",when I give this command :

Bcdedit.exe -set TESTSIGNING ON

I get this error :

The boot configuration data store could not be opened. The volume for a file has been externally altered so that the opened file is no longer valid.

I tried a lot of methods to fix it,but right now unsuccesfully. Can someone help me ? thanks.

Windows 10 Setup
Windows 10 Setup
Windows 10: A Microsoft operating system that runs on personal computers and tablets.Setup: The procedures involved in preparing a software program or application to operate within a computer or mobile device.
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  1. Joy Qiao 4,886 Reputation points Microsoft Employee


    I understand you want to test-signed driver with a digital signature during development but failed with error about BCD, right?

    Try to rebuild BCD after boot into recovery, and then perform the following command:

    • c: (assuming this is where the Boot folder is)
    • cd boot
    • attrib bcd -s -h -r
    • ren c:\boot\bcd bcd.old
    • bootrec /RebuildBcd

    I noticed you said "I have reinstalled Windows 10 from an old backup.", do you mean you created a clone image for Windows 10 system?
    As clone will bring potential system risk and clone image is also out of our support scope, we recommend to setup system with a valid Windows 10 disk or installation media. Or we could capture system image with DISM command line tool after generalized image with Sysprep.

    Capture and apply a Windows image using a single .WIM file



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  2. mario mario 1 Reputation point

    I've fixed the error making the ISO image of my windows installation and then I have reinstalled it using a tool called "WintoHDD". Without this tool it won't work. Infact,I tried several times to reinstall Windows 10 from the USB stick in a EFI mode with an EFI partition style scheme,but it seems not able to create the EFI partition. In addition,it writes some boot values inside the EFI partition of the NVME disk (that I can't disable from the BIOS). I put it as secondary boot disk but it didn't work anyway. Infact windows 10 can't boot if it is installed as a sata disk and if it is not the only disk on the PC or if it is not on the first place. I'm not sure what's the true.