Sysprep not able to validate Windows installation Sysprep is mandatory for FileWave Windows disk imaging. Possible consequences of not sysprepping are outlined by Microsoft here. It accomplishes the following goals to prepare your reference system for capturing the master image. Removes computer-specific info from a Windows installation by doing the following items below - You may find that some Windows functionality no longer works correctly when computer specific info is duplicated between multiple PCs. Generates a new computer SID Sets a new computer name Clears out event logs Runs mini setup to deal with hardware differences Performs a full Windows shutdown when the "/shutdown" switch is specified, which is required on Windows 8 and 10 - Starting with Windows 8, Microsoft added a fast startup feature that helps your PC start up faster after shutdown, even faster than hibernate. Windows does this by saving an image of the Windows kernel and loaded drivers to C:\hiberfil.sys upon shutdown so when you start your PC again, Windows simply loads the C:\hiberfil.sys file into memory to load Windows instead of starting from scratch. When it does this, Windows leaves the main partition hosting Windows in a state that prevents FileWave from properly capturing it. When you sysprep with the "/shutdown" parameter, it performs a full shutdown without generating a hiberfil.sys file and leaves the partition hosting Windows in a state that allows FileWave to capture it. Sysprep can occasionally fail with a validation error due to a provisioned Microsoft Store Appx app being updated automatically by Windows 10. Sysprep has an additional provider in Windows 8 and 10 to clean Microsoft Store Appx packages and generalize the image. This provider will fail if an all-user package is updated for one of the users on this reference computer, which Windows will do automatically if it is connected to the internet long enough. To minimize the the chances of this happening on the reference system, keep it disconnected from the internet as much as possible. The error message you'll see in %WINDIR%\System32\Sysprep\Panther\setupact.log, and more importantly in setuperr.log, when sysprep fails under these circumstances is that "an app was installed for a user, but not provisioned for all users".