[SOLVED] Create EFI partition to make my OS drive bootable.


Dec 31, 2017
I installed windows 10 on my SSD using a external HD while keeping my old HDD with original OS in it. I’d like to remove the HDD (Disk 0 on the image below) and make the SSD (Disk 1) my only OS, but since It doesn't have an EFI partition nor bootable files, is there a way to move/create EFI partition on my new SSD?

What's with those cropped screenshots? Why do you do that every time?

You have created 101MB basic data partition on disk 2. That is not bootable. You have to create efi system partition. And make size 500MB not 100MB.

Execute from elevated command prompt.
list disk
select disk 2
list partition
select partition 3
(select 101MB partition)​
delete partition
select partition 2
(select 136GB partition)​
shrink desired=400
create partition efi
format fs=fat32 quick
assign letter=Y
bcdboot C:\windows /s Y:
verify, you can boot from boot drive alone,​
reconnect all drives and delete efi partition from HDD.​
Edit: Or is it EFI parition, you have created? Can't see, because, you have the screenshot cropped.
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Yeah. That looks good.
101MB efi system is kindda small. It's recommended to have it 350MB or 500MB.
If you run of space on it, then there's going to be trouble. It's possible for some windows updates to fail, if they want to write more data on bootloader partition.

Anyway - if you can't give it more 101MB, then
assign drive letter Y: to 101MB partition,
run bcdboot command from elevated command prompt and
it's done.

Left only verification and cleaning old efi partition from hdd.
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Win 10 Master
You would need to wipe the drive, convert it to the GPT partition table, then reinstall Windows as UEFI.
No, its already GPT now, all that has happened is win 10 saw the EFI partition on hdd and added the ssd to it.

All he needs to do is create an efi on the ssd, and possibly remove the old one from hdd. (depends on if he wants to reuse that install). I know there is a way to do that but I can't remember it. @SkyNetRising knows the steps better than I do.
Your Disk Management top view should show volume list. And it's again not a full screenshot.
Currently I can't see, how much space is used on volumes.

General idea is to:
shrink some partition on boot drive (where OS partition is located) and make enough space for bootloader (500MB is enough),​
create efi system partition in freed up space,​
format it and create bootloader files on it using bcdboot command,​
verify, you can boot from boot drive alone,​
reconnect all drives and delete efi partition from HDD.​
If you need a list of diskpart commands, that does all that, then show
full screenshot of Disk Management window with volume list in top part.
Last edited:
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