The Windows-To-Go creator tool (Wtgcreator.exe) is responsible for imaging a Windows-To-Go USB drive with a Windows Image (WIM) file.
This WIM file may be:
- Taken from a Windows 8.1 original ISO image
- A customised WIM image created using Configuration Manager or the Microsoft Deployment Toolkit (MDT)
To use the tool you simply:
- Plug in your certified USB device
- Start the Windows-To-Go Wizard
- Highlight your USB key and click Next
- Click ‘Add Search Location’ and provide a directory where the WIM file lives
- Select the correct WIM and begin the imaging process
When running through the Windows-To-Go creator wizard, no custom WIM files (even though they exist) are listed which prevents imaging.
Selecting a stock WIM file from the original ISO however works.
Use the DISM command to mount the WIM image to a temporary directory:
"DISM.exe /Mount-Wim /WimFile:C:\images\myimage.wim /index:1 /MountDir:C:\images\mount"
Close the WIM with the commit flag:
DISM.exe /Unmount-Wim /MountDir:C:\images\mount /commit
I don’t know why this works yet, but it does solve the immediate issue.
One interested thing to note is that the WIM file is now around 10MB larger.