Windows 10 won't boot without the old Windows 8.1 drive.

Can't seem to get new Windows 10 drive to boot on it's own.
Windows 10 installed on Disk 0 (according to Disk Management's incrementation).
Windows 8.1 installed on Disk 1 (according to Disk Management's incrementation).
Would like to remove Disk 1 completely and boot Windows 10 from Disk 0.

Not sure why I can't see anything marked as active in Disk Management? upload_2015-9-8_15-58-17.png

While MiniTool Partition Wizard does show an Active & Boot status on the 100 MB EFI System Partition on Disk 2 (according to MiniTool's incrementation).

I tried "Change boot drive" with EasyBCD 2.3 BETA but I get the following error message talking about a logical drive.

Strangely, I didn't even see any logical drives indicated by MiniTool Partition Wizard.

I'm guessing I need some partition on my Windows 10 disk to be marked as Active & Boot but wouldn't I also need an EFI (System Partition) as well? I thought of copying the EFI partition to my Windows 10 disk but didn't know where it should go in relation to the other partitions? Kinda lost.


Knows where his towel is.
Staff member
There is no "active" partition on a UEFI GPT disk,
Active is a flag in the MBR partition table.
The EFI system partition is the UEFI equivalent.
I'm not sure that "change boot drive" works for non-MBR systems, it would have to do things quite differently.
You'll have to wait for mqudsi (the author) to pronounce on that.
I could advise you exactly what to do for your situation on an MBR system, though you seem to know already yourself.
It's not something I've tried since going UEFI, but if you have a W10 re-installation ISO bootable, you could try booting it with the 8.1 HDD disconnected and seeing whether W10 has the equivalent of Vista/7's "repair startup"


Mostly Harmless
Staff member
It's not really going to work if you don't already have the correct partition structure on the destination drive, unfortunately. This is because Microsoft requires 3 other partitions aside from the Windows partition on the destination drive, and EasyBCD can't just repartition the destination drive willy-nilly of its own accord.
Well that's a bummer! I knew EasyBCD doesn't repartition but I was hoping that I could shrink the Windows 10 partition and create the necessary missing partitions and then use EasyBCD to make the drive with the new partitions bootable. Thanks anyway.