Cannot mount vhdx file

cadmasteruk · 2026-10-29T06:37:32-0400

Prior to installing Win11 26H2 I took the precaution of making a disk image of the current 24H2 on an external drive.
The 26H2 defaulted to a clean install so I lost everything on drive C: - most critically my Thunderbird profile and AutoCAD customisation files.
I want to reinstate 24H2 temporarily so that I can back up these to an external location (I have Synology NAS) then reinstall 26H2 and copy the saved files back.
However, when I try to mount the vhdx file from the image I get the notification 'The disk image isn't initialised, contains partitions that aren't recognisable, or contains volumes that haven't been assigned drive letters...'
When I attempt to use Disk Management to assign a new drive letter this option is greyed out.
Am I doing the right thing?
How can I reinstate 24H2 in another way?

kelper · 2026-10-29T06:41:30-0400

How did you make this backup? Give details of the program or commands used.

cadmasteruk · 2026-10-29T07:22:36-0400

I used Backup and Restore (Windows 7) to create an image on an external drive (E:)

kelper · 2026-10-29T07:25:55-0400

I think you may be doing it wrong. Backup & Recovery normally creates a VHD file?

To restore:-

Open Settings → System → Recovery.
Beside Advanced startup, click Restart now.
Select Troubleshoot → Advanced options → System Image Recovery.
Select your Windows account and enter its password if requested.
Windows should detect the system image automatically if the backup drive is connected.
Select the image, then follow the restore wizard.

cadmasteruk · 2026-10-29T07:27:43-0400

In the backup folder (WindowsImageBackup/T5810/Backup 2026-10-20 112458) are three .vhdx files, one is 203GB which I assume is the actual disk image, the second is 952MB, the third (Esp.vhdx) is 471MB.
All three will not mount with the same notification above.

kelper · 2026-10-29T08:03:03-0400

I made a backup like yours and confirm you can't mount the VHDX in Windows 11

pseymour · 2026-10-29T09:10:14-0400

Wouldn't you just click "Restore my files" and browse for folders/files to restore?

hsehestedt · 2026-10-29T10:19:20-0400

pseymour said:
Wouldn't you just click "Restore my files" and browse for folders/files to restore?

I beileve that the OP performed a disk image backup, not a file and folder backup.

Question: Did you look permissions of the VHDX file? It's been many years since I used the disk image feature built into Windows because it has already been deprecated years ago but from my recollection I seem to recall having to mess with permissions. If I get a chance I may try to take a look at it this evening but I likely won't have a chance until then because I've got a pretty busy day ahead today.

Bree · 2026-10-29T10:39:31-0400

cadmasteruk said:
I want to reinstate 24H2 temporarily so that I can back up these to an external location (I have Synology NAS) then reinstall 26H2 and copy the saved files back.
However, when I try to mount the vhdx file from the image I get the notification 'The disk image isn't initialised, contains partitions that aren't recognisable, or contains volumes that haven't been assigned drive letters...'
When I attempt to use Disk Management to assign a new drive letter this option is greyed out.
Am I doing the right thing?
How can I reinstate 24H2 in another way?

With Backup & Restore (Windows 7) each .vhdx is one of your backed up partitions, the largest will almost certainly be your C: partition.

I get the same error on mounting the .vhdx. It is missing a drive letter and, for the C: partition's .vhdx at least, I can add one and get full access in Explorer.

Alternatively, the correct way to restore a Backup & Restore (Windows 7) system image is to boot to Advanced Startup, in Advanced Options you can restore this system image.

Boot to Advanced Startup (WinRE) in Windows 11

This tutorial will show you how to boot to the advanced startup (WinRE) in Windows 11. The Windows Recovery Environment (WinRE) is a companion operating system installed alongside Windows 11, typically in a separate partition, that can help with troubleshooting, recovery, or booting from...

www.elevenforum.com

Bree · 2026-10-29T10:46:39-0400

hsehestedt said:
Question: Did you look permissions of the VHDX file? It's been many years since I used the disk image feature built into Windows because it has already been deprecated years ago but from my recollection I seem to recall having to mess with permissions.

The only permissions you need to change for WindowsImageBackup and its sub folders is to grant access - and Explorer offers to do that for you when you try to open one. The vhdx files themselves have no special permissions, only the folders they are in.

kelper · 2026-10-29T11:26:03-0400

@cadmasteruk
The easiest way to get just the files you want is to use 7-zip (free). It can open many compressed files, including VHDX's, I have just tested it on the backup I made for the sole purpose of helping you.

https://github.com/ip7z/7zip/releases/download/26.05/7z2605-x64.exe

Bree · 2026-10-29T11:57:53-0400

kelper said:
@cadmasteruk
The easiest way to get just the files you want is to use 7-zip (free). It can open many compressed files, including VHDX's, I have just tested it on the backup I made for the sole purpose of helping you.

https://github.com/ip7z/7zip/releases/download/26.05/7z2605-x64.exe

Good call

I've tested it on the one I made too. You just need to open the '1.Basic data partition.ntfs' to find all your files from the C: drive.

pseymour · 2026-10-29T12:31:57-0400

hsehestedt said:
I beileve that the OP performed a disk image backup, not a file and folder backup

I was able to discern that by “ I took the precaution of making a disk image.”

I did a full backup and tested how to get at the files before I said that. But we can keep making convoluted suggestions also.

You can also mount the VHDX files with DISM.

Bree · 2026-10-29T12:52:21-0400

pseymour said:
Wouldn't you just click "Restore my files" and browse for folders/files to restore?

pseymour said:
I did a full backup and tested how to get at the files before I said that. But we can keep making convoluted suggestions also.

If you make a full backup then two completely independent processes take place. The first is a data files backup to a backup set of .zip files. The second is a full system image backup to a set of .vhdx files.

Only if you made a data files backup can you restore individual files in the way you suggested.

We are all assuming that the OP didn't make a full backup, rather that they clicked 'Create a system image' and only has a set of .vhdx files. Windows Backup specifically warns that you cannot select individual items to restore from a system image.

kelper · 2026-10-29T13:06:23-0400

Restore & Backup (Windows 7) does not show me any option to restore files. I think this depends on your having set a backup schedule. I certainly don't see the screen that Pseymour posted in #7.

Bree · 2026-10-29T13:12:31-0400

kelper said:
Restore & Backup (Windows 7) does not show me any option to restore files. I think this depends on your having set a backup schedule. I certainly don't see the screen that Pseymour posted in #7.

You will only see that option if you set up and ran a backup of your data files, first screenshot in my post #14.
You and I just created a system image (second screenshot) so that's not an option for us.

Bree · 2026-10-29T13:17:00-0400

pseymour said:
I did a full backup.....

I do hope you didn't just delete the WindowsImageBackup folder when you were done testing. If so, you'll need to read this tutorial....

When you create a System Image using the built-in 'Backup & Restore (Windows 7)' a special type of Restore Point called a System Image Restore Point is available in System Restore. These will appear alongside the other restore points as 'type Backup' when you tick the box for 'Show more restore points' in System Restore.....

In the case where System Images may have been deleted manually (or the drive they were on is no longer available) these restore points remain but are of no further use. There is no tool available in Windows 10 to remove such orphaned restore points.

Backup & Restore - Delete System Image Restore Point from System Restore in Windows 10

When you create a System Image using the built-in 'Backup & Restore (Windows 7)' a special type of Restore Point called a System Image Restore Point is available in System Restore. These will appear alongside the other restore points as 'type Backup' when you tick the box for 'Show more restore...

www.tenforums.com

kelper · 2026-10-29T13:20:58-0400

Bree said:
I do hope you didn't just delete the WindowsImageBackup folder when you were done testing. If so, you'll need to read this tutorial....

Backup & Restore - Delete System Image Restore Point from System Restore in Windows 10

When you create a System Image using the built-in 'Backup & Restore (Windows 7)' a special type of Restore Point called a System Image Restore Point is available in System Restore. These will appear alongside the other restore points as 'type Backup' when you tick the box for 'Show more restore...

www.tenforums.com

That tutorial seems to have a lot of tags which may confuse noobies?

pseymour · 2026-10-29T13:30:57-0400

Bree said:
I do hope you didn't just delete the WindowsImageBackup folder when you were done testing. If so, you'll need to read this tutorial....

I'm not sure why you would hope that or not hope that. It wasn't a production machine anyway. I simulated what OP did. I took a backup, kept the drive the backup was on, and re-installed the OS.

Bree · 2026-10-29T13:42:32-0400

kelper said:
That tutorial seems to have a lot of tags which may confuse noobies?

Thanks for the heads up. They're not meant to be there! Those are artefacts of @z3r010's emergency migration of the Ten Forums site from the old vBulletin sofware to XenForo. Not everything got translated correctly in that migration. I'm surprise it went as smoothly as it did, under the circumstances - a rush job to combat the PHP vulnerabilities in vBulletin.

I wrote that tutorial, and I've now edited it to remove those spurious tags.

Cannot mount vhdx file

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