I have two hard drives configured as a simple layout storage space in Windows 10 Home. The entire virtual drive is formatted as a single large ReFS partition mounted on D. The other day I enabled Windows Insider updates and ever since I rebooted, I can't access the D drive. It's still mounted, but I get an error message that the drive is not formatted.

What steps can I take to figure this out?

2 Answers 2


This issue was recently discovered in Windows 10 (I work for Microsoft). There is a fix coming, but for now, try to go back to a previous version of Windows and don't upgrade until the fix reaches the Windows Insider Program. If you wait about a month or 2, you should be good.

I don't have enough reputation to comment, so I posted this as an answer even though it doesn't really belong here.

  • I just realized that going back to a previous version of windows likely won't help since the OS upgrade might have corrupted your filesystem. It's still worth a shot, but if you still can't mount the volume after the rollback, we'll probably need to develop a special tool to help repair your ReFS volume. Aug 28, 2017 at 22:11
  • Thanks for this. I ended up reinstalling Windows 10 from scratch and fortunately had backups of almost everything on the ReFS partition. I opted not to enroll the new installation in the Windows Insider program for now, and so far everything is working fine.
    – njbair
    Aug 29, 2017 at 21:26

Here is a procedure that worked for me, at least for the moment :

  1. right click on any/every of the *.vhdx files.
  2. choose MOUNT in the context menu until there is/are no more errormessage/s
  3. open the old (win 7) control panel - choose System and Security and then Storage Spaces and watch the diskpool beeing repaired. Then optimize the pool

The assigned drive is reappearing and one might try to backup the data from there

hope that helped - cheers

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