Why is this page here? 2 reasons… First: We have seen clients bring in Windows 10 computers that would not boot or would not successfully “fix the boot process” using the Windows 10 recovery environment. Second: It is possible to use the process below, as the final step in “cloning” if you do not have a cloning tool. The process assumes 2 disk drives. On a new drive, install Windows 10. Next, using Clonezilla or RescueZilla or ???, copy the Windows partition from the old drive to the Windows partition of the new drive. The result is likely to be that the new drive will not boot. The process's below can fix the boot process on the new drive.

Warning!! Understanding and/or fixing boot failures is tedious, aka “lots of details”. Be careful!!!! If you want to understand the details of the Windows boot process this youtube video is a good starting point. It is about 20 minutes long and full of details. If you just need to repair a boot failure, this video may be what you want to watch. The cliff notes for the video are: From a “cmd” window, use diskpart to assign “C” to the Windows partition. Then invoke “bootsec /nt60 all /force”. Then invoke “bcdboot c:\windows /f ALL”. Then invoke “bootrec /fixmbr”. Then invoke “bootrec /fixboot”. The details in the video start at about the 2 minute mark and finish at about 6 minutes.

And then from here is the snippet below, in bold/italic font. The problems with the snippet were: It assumes the boot folder is in the C drive ,ala Windows 7. Windows 10 keeps the bcd folder in a separate partition, so you need to use diskpart to mount the partition to a drive letter and adjust the commands/steps identified in the snippet. How do you do this?

From a command line:

diskpart

select disk 0

list partition (one of them will be named ESP or System)

select partition NUMBER (use the number of the partition that is System or ESP)

assign (assign will assign a drive letter to the partition that is selected by the previous select.

And then I watched this : UEFI Explained, by the TechSavvyProductions youtube channel and learned about the mountvol command. The simpler way to mount the system volume is:

mountvol e: /s

Note Use the Bootrec.exe tool to troubleshoot a “Bootmgr Is Missing” error. If rebuilding the BCD store doesn't resolve the startup issue, you can export and delete the BCD store and then run this option again. By doing this, you make sure that the BCD store is completely rebuilt.

To do this, type the following commands at the Windows RE command prompt:

Use diskpart to assign the boot partition to a drive letter, assume E:

• bcdedit /export E:\BCD_Backup
• E:
• cd Microsoft\boot change directory to e:\EFI\Microsoft\boot
• attrib bcd -s -h -r make the bcd file visible
• ren bcd bcd.old rename bcd to bcd.old
• bootrec /RebuildBcd This should create a new bcd file

Windows 10 boot configuration can be controlled with bcdedit and bootrec. bcdboot is a program that establishes the contents of the boot/system partition.

How to fix Windows 10 boot problems.

More links about fixing boot problems:

Use bootrec.exe in the Windows Recovery Environment to troubleshoot startup issues.

Restore a lost boot partition.

Windows dual boot can be accomplished with the Windows Boot Manager. Windows boot manager configuration can be done with bcdedit. Microsoft documentation for bcdedit can be found here: Bcdedit documentation was found at microsoft.com after searching for bcdedit.

You can find other tools for configuring Windows Boot Manager. EasyBCD is NOT free. VIsualBcd appears to be free.

Using any of the tools requires some reading and caution.

Why would you want or need to configure Windows for dual boot. My test case is:

I have two hard drives in my desktop. One drive is an SSD, the other is a Western Digital. Occassionally I copy the SSD to the hard drive as a backup. I would like to boot from the Western Digital to verify the copy works.

I have had many dual boot systems, that have Linux and Windows installed. The result is the boot loader for them is grub, not Windows Boot Manager. Grub configuration is a text file, which allows configuration with a text editor. Windows Boot Manager configuration is in a binary file, which leads to the need for a program to configure the boot manager. The Windows 10 boot configuration editor is bcdedit.

First: Google “restore Windows 10 boot partition”. This might lead to one or more of the following.

As suggested by Microsoft .