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Restored vhdx (Hypver-V) unable to mount

Level 3

Hi all,

I'm working for a small charity that has three WIndows Server 2019 hyper-v servers running a couple of VM's.  I have forever incremental backup jobs running that seem to be running fine.  However, after a successful restore, I've discovered that some, but not all, of the restored vhdx files have no partitions or no drive letters assigned when mounted.

When right clicking on a restored vhdx file, one of three things happens depending on the vmdx.

  1. It mounts fine and assigns drive letters - that's the normal behavior that I'd expect.  That does happen with many of the restored files, but not all unfortunately


  2. Frequently I will get this error message


    Couldn't Mount File

    The disk image isn't initialized, contains partitions that aren't recognizable, or contains volumes that haven't been assigned drive letters.  Please use the Disk Management snap-in to make sure that the disk, partitions, and volumes are in a usable state.


    then one of 2 things happens.  Either

    2a. In disk manager, I am asked to initialize the drive.  After doing so there are no partitions on the drive, making it unusable.


    Sometimes I can se the partition(s) on a virtual drive in disk manager, but there's just no drive letter assigned.  I still get the above "Couldn't mount file" message, but I don't need to initialize the drive, it just shows up in disk manager with no drive letters.  This is pretty infrequent, it's usually 2a when I have a problem VHDX.  When I can see the partitions, I can assign a drive letter, but I'm not sure what would happen if that VHDX file were used as a restoration that was to be spun up in Hyper-v

Has anyone seen this before?  I've not on any of the other servers I manage elsewhere with a very similar configuration.  

I should add that for each vm, all restored vhdx files for that vm will either all be okay, all have no partitions, or all have partitions but with no drive letters.

I did create a NEW forever incremental backup for each of the 3 servers.  I ran a new backup on one to test, then did a restore.  3 vm's restored fine where I could open the vhdx file, 3 gave me problem 2a above, and one gave me problem 2b.

Any suggestions as to why this is happening and/or what I might be able to to stop it?  No point in backing things up if the restores are unusable!!


Thank you all






Request you to perform below two validations:

  • Try GRT Restore of data on particular VHDX which you are trying to restore.
  • Also, try and perform Instant Recovery of that VM and validate the VHDX content from backup sets.

Do let me know the results.