Moved my EFI System Partition to another drive but Windows still boots

BrokenKeyboard

I was cleaning up my disks and noticed that my EFI System Partition isn't on the same SSD as my Windows installation.

A while ago I cloned Windows to a new NVMe SSD, and somehow the old SATA SSD still contains the EFI partition. Windows boots perfectly fine right now, but I'm worried that if I remove the old drive, my PC won't start anymore.

Current setup:

Disk 0: 1TB NVMe (Windows 11 installed)

Disk 1: 500GB SATA SSD (contains EFI System Partition)

BIOS mode: UEFI

GPT disks

Questions:

Is it normal for Windows to boot like this?

How can I confirm which EFI partition is actually being used?

Can I safely move or recreate the EFI partition on my NVMe SSD without reinstalling Windows?

What's the safest way to avoid ending up with a "No Bootable Device" error after removing the old SSD?

I've seen a lot of guides mentioning bcdboot, DiskPart, and Startup Repair, but I'm not sure which method is the least risky.

Has anyone gone through this before?

LeoF_225

BrokenKeyboard That's actually possible. Windows doesn't magically switch to the new EFI partition just because one exists.

The firmware boots whatever boot entry is stored in NVRAM. If that entry still points to the EFI partition on the original drive, Windows will keep using it without caring that you copied or moved another ESP elsewhere.

Did you actually rebuild the boot files on the new EFI partition (bcdboot) or only copy the partition?

MarkBuilds

BrokenKeyboard People often say they "moved" the EFI partition when they actually mean "copied" it.

Those are not equivalent operations.

Until the firmware boot entry is updated—or recreated—the existence of another valid ESP doesn't change the boot path. The partition itself is only one piece of the process.

PacketFlow

BrokenKeyboard Following because I always assumed Windows would automatically detect the "new" EFI partition after moving it.

Apparently it's a lot less automatic than I thought.

MarkBuilds

BrokenKeyboard One more thing worth checking:

If both drives now contain valid EFI System Partitions, leaving both connected can become confusing later. A BIOS reset or firmware update may reorder boot entries and suddenly the machine boots differently.

I generally prefer having only one active boot target once everything has been verified.

AnnaM89

LeoF_225 +1 to this.

I cloned an EFI partition once and thought I was done. Turns out the machine was still booting from the old SSD the whole time.

The easiest test is just disconnect the original drive temporarily. If Windows suddenly refuses to boot, you'll know which EFI partition is actually in use.

FilmNightFan

AnnaM89 Windows boot logic basically goes:

"Oh cool, a shiny new EFI partition."

"...Anyway, I'm gonna keep using the old one."

It has the same energy as people buying a new couch and still sitting in the broken chair.

LeoF_225

MarkBuilds Exactly.

There are really three separate things involved:

the EFI partition

the boot files inside it

the firmware boot entry

People usually only think about the first one.

If any of the other two still reference the original drive, that's the one your PC will continue booting from.

AnnaM89

PacketFlow It usually isn't automatic.

When I migrated from HDD to NVMe, I had to recreate the boot files on the new drive before I could remove the old disk. Until then everything looked fine because the BIOS silently kept loading the old EFI partition.

Easy thing to overlook.

LeoF_225

MarkBuilds Agreed.

After confirming the new drive boots independently, it's worth checking the firmware boot order and making sure the new Windows Boot Manager is first.

That avoids surprises months later when you forget which disk is actually responsible for booting.

FilmNightFan

LeoF_225 The number of PCs surviving purely on "don't unplug that old SSD" is probably way higher than anyone wants to admit.

Everything works... until someone decides to clean the case.

PacketFlow

BrokenKeyboard This thread explained it better than a lot of blog posts I've read.

My takeaway:

Copying an EFI partition doesn't automatically make it the boot partition.

The firmware still decides what gets loaded.

Test by booting without the old drive before calling the migration finished.

Good info to know before I try moving mine.