Before you can edit, change, or update an image, you have to mount an image first. Mounting an image connects it to a folder where, once the image is mounted, you can service the image, which means that you can add features or update drivers. A WIM file can contain multiple operating system images, but you can mount only one image in a file at a time. Each operating system image has its own identifier, which is a number that you refer to when mounting an image. If, for example, a Windows Server 2018 ISO file is extracted to a folder called c:en_windows_server_2016_x64, the install.wim image is located in the sources subfolder, and you can list the operating files it contains using one of the following commands:

DISM.exe /get-imageinfo /imagefile:c:en_windows_server_2016_x64sourcesinstall.wim 

Or, alternatively, the following command:

DISM.exe /get-wiminfo /wimfile:c:en_windows_server_2016_x64sourcesinstall.wim

Alternatively, you can use PowerShell:

Get-WindowsImage -ImagePath c:en_windows_server_2016_x64sourcesinstall.wim

These three commands produce the same result. The following screenshot shows the output of the dism.exe command:

The following screenshot shows the output of the PowerShell command:

Note the Index field in the dism.exe output and the ImageIndex field in the PowerShell output and their values. Each operating system installation has it own unique identifier or index entry. The Windows Server 2016 Standard installation has index entry 1, the Windows Server 2016 Standard (Desktop Experience) installation has index entry 2, the Windows Server 2016 Datacenter installation has index entry 3, and the Windows Server 2016 Datacenter (Desktop Experience) installation has index entry 4.

Once you have identified the working Windows installation, mount it using the following commands:

DISM.exe /mount-image /imagefile:c:en_windows_server_2016_x64sourcesinstall.wim /index:4 /mountdir:c:mount

Alternatively, you can use the PowerShell alternative:

Mount-WindowsImage -ImagePath c:en_windows_server_2016_x64sourcesinstall.wim -Index 4 -Path c:mount