If your Windows image is unserviceable, the DISM (Deployment Imaging and Servicing Management) tool can help you fix the issue. DISM is a command-line tool that prepares and repairs Windows images (.wim) or virtual hard disks (.vhd and .vhdx). It can also help you prepare a Windows Preinstallation Environment (Windows PE).
This tool is inbuild on your Windows system, and you can access it easily from the Windows PowerShell or Command Prompt. DISM commands vary based on the edition of Windows you want to server, as well as the state of the image (offline or online).
However, many users have experienced issues when using the DSIM command-line tool to repair or prepare Windows 10 image backup on an external drive. They get the following error message when they attempt to perform the operation:
On this page, you will learn the correct way to run DISM on an external drive to repair Windows 10 image backup.
Run DISM Offline to repair Windows 10 System Image backup
First, run the following command:
Dism.exe /Online /CheckHealth
When you use the /CheckHealth argument, the DISM tool will report whether the image is healthy, repairable, or non-repairable.
- If the image is non-repairable, you should discard the image and start again.
- If the image is repairable, you can use the /RestoreHealth argument to repair the image.
If the DISM tool doesn’t work, then you have to clean up the Windows system components.
Press the Windows key and search for cmd. Right-click on Command Prompt and run it as an Administrator. In the Command Prompt window, type the following command and hit ENTER:
Dism.exe /Online /Cleanup-Image /RestoreHealth /Source:C:\RepairSource\Windows
NOTE: In the command above, substitute the
C:\RepairSource\Windows part with the actual location of the repair source.
Run DISM offline
If you are looking to repair an offline image with the use of a mounted image, you can use:
Dism /Image:C:\offline /Cleanup-Image /RestoreHealth /Source:C:\test\mount\windows
You could also use
/LimitAccess at the end to prevent the DISM tool from using Windows Update as a repair source or as a backup repair source for online images.
These simple commands will resolve the issue and successfully let you use DISM on external drives.
TIP: You can also fix corrupted Windows Update system files using DISM Tool.