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I don't know how I come to this but the partition I use to install Windows 7 64-bit is hidden. It is also a EFI System partition (I saw this using the Disk Management tool).

Since the Windows partition is hidden, I cannot boot into it and also can not repair.

Is there any solution ?

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  • I am confused here. How is it hidden? Since you mentioned EFI it should be a GPT partitioned disk and a EFI system partition. Those are compativle with FAT32 and windows 7 supports FAT32. SO access should just work. Worst case it can be accessed but is not mounted. Can you add precisely what happens?
    – Hennes
    Sep 12, 2016 at 16:38
  • It appears the OP somehow installed Windows to the ESP. While theoretically possible, this is not a supported scenario with Windows.
    – Daniel B
    Oct 13, 2016 at 6:21

2 Answers 2

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Do you have any other OS installed on your system which you can boot into? If yes, then for Windows OS, download and install MiniTool Partition Wizard Home Edition (or any other partition manager that allows editing partition flags), and in it, right click the partition you want to unhide (Windows 7 partition), go to "Modify" > select "Unhide patition". For Linux OS, get GParted, and remove "hidden" flag of your Windows 7 partition.

In case you do not have any OS to boot into, get GParted Live by some way, burn the ISO to disk, boot your system to GParted Live disk, and remove "hidden" flag of your Windows 7 partition.

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Using DiskPart you can unhide an EFI partition on a GPT volume:

Diskpart>
list volume
select volume #
detail partition
set id=EBD0A0A2-B9E5-4433-87C0-68B6B72699C7

The default GPT ID for a EFI System partition is c12a7328-f81f-11d2-ba4b-00a0c93ec93b, converting to a Basic data partition with the ID ...C7 automatically unhides the partition.

I have had success with this command prior, but I believe it was for MBR (msdos) partition table.

attributes volume clear hidden

Failure to change the partition type before clearing the hidden attribute, results in this diskpart error message:

Virtual Disk Service error:
The object is not found.

You most likely want to set the ID back to EFI when you are done (eg: modifying BCD)

set id=c12a7328-f81f-11d2-ba4b-00a0c93ec93b
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  • For some reason, os-uninstaller (part of boot-repair-disk) changed my Windows 10 main partition into an EFI System Partition, preventing Windows from booting. Applying these steps made Windows immediate start booting successfully.
    – Wesley
    Apr 19, 2020 at 0:09

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