daknetworks.com

I used Disk2VHD to create a P2V. Then I started Hyper-V and created a new VM. Upon startup I got, "Missing Operating System."

Here's how to fix:

-connect Windows 10 iso (or a Windows repair disk).
-press any-key to boot via iso.
-wait for windows 10 to show (it could take a minute).
-select Windows 10.
-select your language.
-click NEXT.
-select REPAIR YOUR COMPUTER (bottom left).
-click NO (for automatic repair).
-click NEXT (at bottom right).
-click COMMAND PROMPT.
-type: bootrec /scanos.
(If it isn't already there, it should find the WINDOWS installation and ask if you want to add it.)
-type: Y

Now, at this point, if you try to do some work in bootrec (rebuildbcd), you will get a message, ""the volume does not contain a recognized file system."

-type: Diskpart
-type: LIST DISK
-type: SELECT DISK 0 (change this to the number of the disk . most likely 0)
-type: LIST PARTITION
-type: SELECT PARTITION 3 (change this to your partition number. most likely 3)
-type: DETAIL PARTITION
(it will show the details of the partition. We're trying to find the partition with the windows installation.)
-if you found it, it will probably say ACTIVE: NO
-type: ACTIVE
-type: EXIT

-type: bootrec /fixmbr (needed?)
-type: bootrec /fixboot (needed?)
-type: bootrec /rebuildbcd
-type: exit
-click RESTART

-boot from the iso one more time.
-click STARTUP-REPAIR.

It should find the Windows 10 installation and fix itself.

NOTES:

This is the same set of instructions for this article: http://www.daknetworks.com/blog/221-clone-macbook-pro-hard-drive-with-boot-camp