In the case of a failed upgrade, it is better to delete the folder and start the upgrade process afresh. The $Windows.~BT and $Windows.~WS folders are created by Windows, during the upgrade process.

Search for the folder $WINDOWS.~BT in the C: drive.

Check the option for hidden files as in the image below.

To do this, open the File Explorer and among the tabs on the top, select the View tab.

Make Windows show Hidden files & folders.

Other than those steps, a few of the following could be tried as well: 1] Delete the folder $WINDOWS.~BT In such a situation, please try the basic steps which are followed when a Windows Update fails to install. Some users said that it installs half or 75% of the update and then restarts abruptly. Usually, the system reboots without the upgrade.

Though there may or may not be an error message specific to this issue, the OS may fail the upgrade and revert to the previous version after a few flashes on the system. If you are unable to install the latest Windows 10 version on your system then this post may help you.

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