When you apply Windows 10 feature updates or upgrade to a new
version of the OS, Microsoft creates a folder called
“Windows.old” to save a copy of the previous version for
If the update installation fails or
Windows is unable to boot with Blue Screen error, you can
use the Windows.old folder to go back to the previous or
current Windows installation.
Windows.old folder can consume up to 20GB of your disk space,
but it can be less or more depending on the number of apps,
files and customization included in your previous installation.
To delete Windows.old folder, Microsoft recommends visiting
Disk Cleanup tool where you need to click “Cleanup system
files” button and then select “Previous Windows
The tool will automatically calculate space those files are
taking up and you can click on “OK” to wipe the previous
Windows system files and free up storage. This process is very
straightforward, but it may not work for everyone, according to
the tech giant.
In some cases, Disk Cleanup won’t remove the ‘Windows.old’
folder and users have been reporting the problem for several
months. The bug was first reported and fixed in 2016, but it
reappeared for some users after recent updates.
With this week’s preview build, Microsoft says it has finally
resolved an issue that prevents removal of Windows.old folder
for some people when they use Disk Cleanup.
“We fixed an issue where the windows.old folder is not
completely deleted when performing disk cleanup,” Microsoft
noted in the changelog of Windows 10 Build 20257.
It’s worth noting that the fix is currently available for the
testers in the Windows Insider program only.
Although Microsoft is yet to announce a release date for the
undeletable Windows.old folder fix in production channels, it’s
expected to land later this year or early next year.
If you’re unable to remove the folder using Disk Cleanup, you
can head to the Settings app and navigate to Storage Settings.
In the Storage Settings, select Temporary files and remove
unnecessary files taking up space on your system drive.