I have a Tablet with Windows 8.1 Bing 32Bit and 23.5GB usable disk space. Windows Update is offering me the Windows 10 Upgrade. Currently 17.5GB of said disk space are used and 6GB are free, but the updater tells me, that it needs 8GB of free space.

Last week I was impatient and tried to force the Windows 10 Upgrade with the MediaCreationTool without success. I ended up having the infamous "Something Happened" error. Then I tried the "AllowOsUpgrade" registry key variant which brought me so far that the updater downloaded the windows 10 upgrade files. The final step didn't work though and the update process stopped with an error code.

Now that I received the regular update notification, I try to free the necessary disk space. I am stuck though. There isn't anything left to delete (ran CCleaner and checked with windirstat), but there are the two folders $Windows.~BT and $Windows.~WS. Both have a file called install.esdthat uses 2GB and $Windows.~WSalso has a installx86.esd that takes another 2GB. As far as I understood it, one of the two folders is used by the MediaCreationTool and one by the regular Windows Update. So what I am looking at is a possible duplicate of the necessary upgrade files and that duplicate would be eating up my disk space. Obviously I would like to delete the unnecessary installation files. But which one can be deleted safely without compromising the regular upgrade process?

  • 1
    The obvious solution is delete both. Any requires files at that point would be downloaded. Of course if you got "Something Happened" with the manual method your likely going to get it with the Windows Update method.
    – Ramhound
    Aug 6, 2015 at 10:52
  • Obviously, but I wanted it to upgrade during work, where I am not able to access the corporate network with a private device or download several GBs via my data plan. ;) Aug 6, 2015 at 11:12

1 Answer 1


When I did the update with media creation tool it used the ws folder. I deleted the BT folder.

Deleting the bt folder didn't have any effect on the upgrade. It took around 45 mins from desktop to desktop.

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