I just cloned a hard drive partition (of Windows 10) to a new hard drive.

The thing is that I did it wrong and I just copied the data part, NOT the boot part. So now I have a new hard drive with a Windows copy with no boot partition.

I tested many tutorials, but the problem is that the bootable part NEVER existed on the new hard drive (so it can't be recovered!).

If someone knows how to create from scratch a new bootable partition for Windows 10. I have many licensed programs and lots and lots of configuration.

And if someone asks I just deleted all the data from the old hard drive (genius!), so I can't copy now the bootable disk partition.

  • 1
    Can you install Windows on the new drive (that will create the boot sector) then clonde the old disk over the top of that install?
    – Burgi
    Dec 5, 2019 at 12:40

1 Answer 1


There are general steps in the BCDBoot docs: https://docs.microsoft.com/en-us/windows-hardware/manufacture/desktop/bcdboot-command-line-options-techref-di#repair-the-system-partition

For UEFI the partition layout is documented at: https://docs.microsoft.com/en-us/windows-hardware/manufacture/desktop/configure-uefigpt-based-hard-drive-partitions

  1. Create a new "system" partition of approximately 250 MB:

    DISKPART> create partition efi size=250
  2. Format using FAT32, and assign a temporary drive letter:

    DISKPART> format quick fs=fat32 label="System"
    DISKPART> assign letter="S"
  3. Install the files needed by Windows boot manager, together with an UEFI NVRAM "boot entry":

    C:\> bcdboot C:\Windows /s S: /f UEFI

    (Change "C:" to whatever drive letter is assigned to the OS partition at the moment.)

For BIOS the partition layout is documented at: https://docs.microsoft.com/en-us/windows-hardware/manufacture/desktop/configure-biosmbr-based-hard-drive-partitions

  1. Create a new "system" partition of approximately 100 MB:

    DISKPART> create partition primary size=100
  2. Format using NTFS, and assign a temporary drive letter:

    DISKPART> format quick fs=ntfs label="System"
    DISKPART> assign letter="S"
  3. Set the 'active' or 'bootable' flag for this partition:

    DISKPART> active
  4. Install a partition boot sector:

    C:\> bootsect /nt60 S:
  5. Install a compatible MBR boot sector to the whole disk:

    C:\> bootsect /nt60 S: /mbr
  6. Install the files needed by Windows boot manager:

    C:\> bcdboot C:\Windows /s S: /f BIOS

    (Replace C:\Windows with the actual path to your Windows installation.)

  • "bootsect S: /nt60" could be this command wrong?
    – Joan
    Dec 5, 2019 at 12:48
  • Couldn't bcdboot be something other than C:\Windows as they currently won't be able to boot? If they are fixing it from PE (as described in your first link) it may be bcdboot D:\Windows /s S: depending where it was mounted. Similarly if fixing from another instance of Windows it would be something other than C:.
    – lx07
    Dec 5, 2019 at 12:53
  • im using the windows installer cmd
    – Joan
    Dec 5, 2019 at 12:57
  • C:\> bootsect /nt60 S: C:\> bootsect /nt60 S: /mbr --> There was a small error
    – Joan
    Dec 5, 2019 at 13:19
  • 1
    This worked for me! However, I had to switch order of arguments here: C:\> bootsect S: /nt60 changes to C:\> bootsect /nt60 S: and my Windows drive letter was E so in the last step ensure you are using the correct drive.
    – Alqio
    Oct 13, 2022 at 14:20

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