Missing EFI system partition, can I clone it?

By jweikelinteractive ·
I recently upgraded my desktop and had to do a clean install of Windows 10 on an SSD formatted as GPT. I have my old HDD still hooked up.

Here's where it gets weird: I somehow managed to install Windows on the SSD with no EFI System partition being created in the process. *Everything works fine right now* (I'm on the machine now while posting this), but when I unplug the HDD - the only drive with an EFI system partition - the desktop doesn't boot.

So the question is: what should I do now? Should I try cloning that partition over to my SSD? If so, can I just use Macrium Reflect and clone it to the end where my unallocated space is? (I'm aware I can use diskpart to create the EFI partition, but I'd rather just clone it if I can)

Or, should I just leave everything alone since it's working - I just can't remove the HDD or format it?

Diskpart list partition for my SSD is:
Part 1: MSR 16 MB, Offset 1024KB
Part 2: Primary 953 GB (I haven't shrank this yet), Offset 17MB
Part 3: Recovery 517 MB, Offset 953 GB
best answer
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How I solved it

by jweikelinteractive In reply to Missing EFI system partit ...

Thanks for the helpful answers. I ended up having a third disk drive to run as a mule, making the process super easy and safe:

1) Connected the third "mule" drive
2) Copied the EFI, Recovery, and whatever the unformatted partition from the hard drive mentioned above to the mule
3) Copied the C: drive from my SSD to the mule
4) Unplugged everything except the mule to confirm it could boot with no issues
5) Wiped the SSD and copied everything over from the mule
6) Confirmed the SSD worked

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All Answers

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This one.

by rproffitt Moderator In reply to Missing EFI system partit ...
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by jweikelinteractive In reply to This one.

I'll give this article a shot and report back. My HDD has a corrupt image on the primary partition on it, so I think my plan is to:

1. Remove the primary partition from the HDD
2. Clone the healthy primary from the ssd to it to have in case anything goes wrong
3. Unplug the SSD to confirm the HDD is working properly as a backup
4. Reconnect the SSD and follow the article as provided

I'm worried completely wiping and over writing the HDD would leave me with a system that doesn't boot, and I don't have a third drive to act as a mule

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Remember that without backups.

by rproffitt Moderator In reply to Thanks!

You are now a circus performer doing the high wire act without a net.

It may be OK or not.

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Or, if you prefer another way.

by Kees_B Moderator In reply to Missing EFI system partit ...

1. Disconnect the HDD
2. Reinstall Windows 10 on the SDD.
3. Restore your data on the SDD from your backup.
4. Connect the HDD.
5. Remove the unneeded EFI-partition on the HDD

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