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I am having trouble accessing the EFI partition on windows 10 I tried this method in cmd (I used Administrative privileges ):

open cmd as admin...

diskpart
sel disk 0
sel part 1 (efi part)
assign letter=b
exit
taskkill /im explorer.exe /f
explorer.exe

But it is not working since windows 10, I used this method fine on 8.1.

this picture shows the error I get when I try to access the partition

enter image description here

11
  • How is it "not working"? Some errors, or nothing happens after these steps?
    – gronostaj
    Sep 1, 2015 at 11:03
  • I am able to see the mounted partition but I can't access it.
    – Raffi CH
    Sep 1, 2015 at 11:04
  • Why are you trying to access the EFI partition exactly?
    – Ramhound
    Sep 1, 2015 at 11:11
  • @Ramhound because I have multiple operating systems, and should rename a file so I can access the other system.
    – Raffi CH
    Sep 1, 2015 at 11:13
  • 2
    Interestingly I find that the mounted EFI drive is accessible from the ‘Browse’ button from Task Manager -> ‘Run New Task’ You can then perform basic operations possible with Context Menu (Copy/Paste etc) and even when you run other apps with Admin Privileges e.g. Notepad.exe it can also access the drive from its file menu. The issue seems to be with Explorer.
    – patkim
    Sep 3, 2015 at 8:51

3 Answers 3

29

Try the following, which works in Windows 7 and 8, but I can't promise anything with 10:

  1. Open an Administrator Command Prompt window by right-clicking the Command Prompt icon and selecting the option to run it as Administrator.
  2. In the Command Prompt window, type mountvol P: /S. (You can change P: to any unused drive letter; that's arbitrary.)
  3. Use the Command Prompt window to access the P: (EFI System Partition, or ESP) volume.

You'll need to use text-mode commands, rather than the GUI, but this method should work.

Another alternative is to use another OS. Even if you can't boot your other OS now, which you strongly imply, you might be able to use an emergency disk. An Ubuntu installation medium, for instance, should let you access the ESP pretty easily. IIRC, it should show up as a volume in the lower-left corner of the screen; or you can use the standard Linux mount command to mount it in any way you like.

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  • 1
    Doesn't work mate
    – Raffi CH
    Sep 2, 2015 at 23:09
  • 1
    I tried it with a vanilla install of windows 10 1151 64 bit (i.e. not an upgrade from windows 7.). The mounting part worked fine, but the entire directory is read-only! What's the point in that? Well, it worked a bit. Do you know how to make it read-write? Nov 21, 2015 at 13:56
  • 1
    This worked for me in Windows 10, recovery mode. Thanks! Feb 10, 2017 at 12:09
  • 1
    I get an error mountvol P: /s The parameter is incorrect.
    – Damian
    Oct 6, 2018 at 9:56
  • 4
    mountvol p: /S works fine in admin powershell, win10. Allowing you to browse and edit the partitions files in the cli, but not explorer Mar 13, 2020 at 18:57
22

The answer is by @pat2015 :

Interestingly I find that the mounted EFI drive is accessible from the ‘Browse’ button from Task Manager -> ‘Run New Task’ You can then perform basic operations possible with Context Menu (Copy/Paste etc) and even when you run other apps with Admin Privileges e.g. Notepad.exe it can also access the drive from its file menu. The issue seems to be with Explorer.

4
  • Upgraded to Windows 10 Anniversary edition and this permission trouble started. This workaround worked perfectly. I'm guessing doing some kind of "RUNAS" to behave as a SYSTEM user might work as well, but that's no fun. Maybe I'll do that if every other Windows update breaks my bootloader again.
    – dragon788
    Sep 26, 2016 at 2:00
  • Windows 10 Creators update fixed this problem. Jun 11, 2017 at 14:29
  • 2
    You can also just open the cmd.exe as administrator and use the command line like the good ole dark ages.
    – user148298
    Mar 29, 2018 at 15:46
  • Task Manager solution working in 2021. Using a Hackintosh while in Windows I was unable to access the EFI partition via Explorer and CMD had access denied with elevated privileges Mar 17, 2021 at 9:59
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Update

in Windows 8.1, Windows 10 and Windows Server starting as of 2012 R2 you can use the following Powershell oneliner for getting Read-Write access to EFI partition:

start ((Get-Partition | ? IsSystem).AccessPaths[0])

Original answer

I have found more straightforward way of getting read/write access to EFI partition from Windows 10:

  1. Open an Administrator Command Prompt window by right-clicking Start button and clicking on Command Prompt (Admin)
  2. In the Command Prompt window, type mountvol, disregard help message in the beginning and notice the list of GUID-based paths of all volumes known to Windows, eg.:

list of volumes' GUIDs

  1. GUID of EFI partition is one of those marked with "NO MOUNT POINT" description - in my case it was the first volume
  2. type start \\?\Volume{.......-....-....-....-...........}\ (of course replace dots with the exact GUID from step #3) and new explorer window will pop up with the contents of EFI partition and read/write access to it - voila!

EFI partition in explorer

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  • 1
    How do one unmount the volume safely again?, the description on /P sounds destructive?
    – neslekkiM
    Jun 7, 2017 at 6:38
  • @neslekkiM it is not get mounted, just close explorer
    – maoizm
    Jun 29, 2017 at 5:39
  • Once you have assigned a drive letter P to the efi partition you can exit diskpart and use the usual cmd commands like P:>dir which will list whats on P and so forth.
    – Jens
    Oct 23, 2018 at 13:34
  • 1
    There is a corner case to this, where there are multiple EFI partitions present (for example, when someone attaches a second drive that contains a previous EFI partition). I believe this will not be able to differentiate between the two, with just the approach above.
    – Will I Am
    May 3, 2019 at 14:45
  • @WillIAm You are right, there will be >1 objects returned by the expression. Selector to choose correct disk drive should be added. Unfortunately I do not have access to any Windows hosts to check
    – maoizm
    Jan 22, 2021 at 4:29

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