Sysprep was not able to validate your Windows installation. Review the log file at %WINDIR%\System32\Sysprep\Panther\setupact.log for details. After resolving the issue, use Sysprep to validate your installation again.When I read the log file, I found this:
Package 9E2F88E3.Twitter_126.96.36.199_x86__wgeqdkkx372wm was installed for a user, but not provisioned for all users. This package will not function properly in the sysprep image.So, apparently the Twitter app that is included by default is causing my issue. I did some research and found references to other packages causing the same issue if Windows 10 communicates with the Internet. The VM I'm using does have Internet connectivity.
To remove the app, I ran the following command. Note that you can use wildcards in PackageName for Get-AppxPackage, such as *twitter*.
Get-AppxPackage PackageName | Remove-AppxPackage
When I ran Sysprep again, I got the same error, except this time it was Candy Crush instead of twitter. After removing Candy Crush in the same way, Sysprep ran fine.
I should note, that I never ran or started either of those applications. So, it seems that it may be a best practice for Windows 10 to prevent your base images from communicating on the Internet. After performing one Sysprep, I was able to run Sysprep additional times.
I think this may have to do with live tiles in the Start menu. Both Candy Crush and Twitter are listed in the Start menu.