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I have just cloned my Win 10 PC from a 256GB M.2 SATA SSD to a 512GB NVMe SSD, and it of course would not boot immediately after. I have been learning about and trying to restore/rebuild/create a new BCD, that points to the proper new device and paths. It seems like so far when I bcdedit /import or bcdboot /rebuildbcd , it just concatenates this info onto the existing, bloated, and incorrect BCD entries (Device Not Found, and other errors).

In the end, I'd like to just clear out the whole BCD, as I've made a new one from scratch that I'd like to try. Most instructions I've found on how to do this instruct the user to go to C:\boot\bcd, backup, and erase things. But, that folder doesn't exist on my cloned C: partition.

It also doesn't seem to exist on my (working) Windows 7 laptop, or the (working) Win 10 ultrabook. I believe the W7 is MBR, while the ultrabook and the old and new W10 PC are all GPT, but I am only just starting to understand NTLDR (<= WinXP) vs BOOTMGR (Vista,7,8,10) and MBR/BIOS vs GPT/UEFI, so I may have missed something.

Why can't I find this folder? Is it supposed to exist? Where else can the active BCD store files physically reside? Were all these instructions just for Win10 MBR, and not GPT? Is that even the difference?

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  • Your best option would be to overwrite completely the boot sector, with the "bootsect /nt60 all /force" command from command line in the installer.
    – user1019780
    Commented May 15, 2020 at 11:05
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    if c:\boot does not exist, then its content is inside a small partition hidden away to the user. By default, if you install windows to an empty drive with no partitions, windows will make several partitions, one is the boot partition. If you create the partition yourself and windows can't create the partition, it will mark your C drive as boot drive, and create the boot manager in C:\boot.
    – LPChip
    Commented May 15, 2020 at 11:13
  • @Didier Ah, I buried the page on bootsect under about twenty tabs: docs.microsoft.com/en-us/windows-hardware/manufacture/desktop/… That Microsoft page only mentioned it being used up through Windows 8... I was uncertain if it also applied to Win 10. Now that I've spent another day reading up on this, I am more comfortable with it and will give it a try, thanks!
    – Dan C
    Commented May 15, 2020 at 11:16
  • \boot should exist on the system partition if the OP cloned an entire system drive onto his new disk. This folder should be at the root of the drive, not on a separate partition, visible or not.
    – user1019780
    Commented May 15, 2020 at 11:17
  • @LPChip That would be the EFI System Partition, 16MB or 128MB depending on the OS? It did indeed exist from my original Windows install, along with the Microsoft "reserved" 100MB partition, before the actual OS partition. I have in the past day deleted and reallocated both of those... maybe that brought some of my trouble?
    – Dan C
    Commented May 15, 2020 at 11:18

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When you let Windows create partitions as it wants, it will create a separate boot partition that contains Windows Boot Manager as well as the BCD data store. This partition will not be mounted by default. With GPT, this data resides in the EFI System Partition (ESP), which is of course also a separate partition.

You can mount the ESP (and probably also the MBR-style boot partition) using the mountvol command-line tool. It requires admin rights, so remember to start Command Prompt as admin.

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  • Aha... now I am looking deeper and I see it. When Windows gets to partition and organize boot files like this, the active BCD store seems to be: $[EFI System Partition]:\EFI\Microsoft\Boot\BCD ... this \Boot is the equivalent of the C:\boot directory other instructions have referred to.,,
    – Dan C
    Commented May 15, 2020 at 11:59

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