What is the $WINDOWS.~BT Folder and Why is it Needed?

The $WINDOWS.~BT folder is a hidden system directory that appears on the Windows system drive after an operating system update. You’ll typically find it when upgrading to newer versions of Windows or after installing major updates. This folder contains temporary files used during the update process and can also store files from previous Windows versions, allowing you to revert if needed.

Why Does the $WINDOWS.~BT Folder Exist?

The contents of the $WINDOWS.~BT folder may include:

  • Installation files for Windows and updates that were needed during the OS update process;
  • Logs and temporary files created by the system during the update;
  • Data for restoring the previous OS version, useful if the update fails or the user wishes to revert.

Can You Delete the $WINDOWS.~BT Folder?

It is possible to delete this folder, but only if you're certain you won’t need to revert to an older version of Windows or troubleshoot any issues with the current version. To safely free up space on your drive, use the “Disk Cleanup” tool:

  1. Open “File Explorer” and right-click on the system drive (usually C:), then select “Properties.”
  2. Click “Disk Cleanup,” then select “Clean up system files.”
  3. Check “Previous Windows installations” and any other unnecessary files to free up space.