Cannot sysprep Windows 10 21H1 enterprise edition. Error displayed is:
Dialog error: Sysprep was not able to validate your Windows Installations. Review the log file at %WINDIR%\System32\Sysprep\Panther\setupact.log for details. After resolve the issue. use Sysprep to validate your installation again.
Windows client machine did not have a valid Microsoft License applied
In this case the client machine needed the MAK keys to register the machine. the next attempt sysprep ran as expected.
License verification can be called with command slmgr /dlv