what is $windows-bt
Windows 10: What is the $WINDOWS.~BT folder used for? This folder is used by the Windows 10 Updater, it contains update logs and files downloaded by the Windows update process. How to delete the $WINDOWS.~BT folder? The folder can be deleted e.g. when an upgrade from windows 7 / 8 to Windows 10 failed and you want to free up space on the hard disk.