I found Windows.old folder (23 GB) on my system drive after the recent major Windows 10 update. I haven't recently installed a new operating system, I moved to Win 10 a year ago and I did a fresh install.
Can the folder be created after Windows updates and can I safely delete to save disk space?

  • The Redstone upgrade counts as a major upgrade, just like the 1511 upgrade. – Daniel B Sep 25 '16 at 9:31

The Windows.old folder contains the files from previous OS or version, and is used when the user wants to rollback to the previous OS or Windows 10 version. This folder automatically clears in ~30 days after you upgrade to Windows 10.

If the folder was created when you installed version 1607 (Anniversary Update), the folder might be removed automatically in 10 days.

If Windows doesn't clear the Windows.old folder for some reason, you may remove it it manually using Disk Cleanup (cleanmgr.exe - run as administrator), and clearing Previous Windows installation files.

Recovering data from Windows.old

If you find some of your settings are lost after upgrade, you should be able to recover the program specific data files from Windows.old (ProgramData and AppData folders). Move everything you need, to a different folder outside Windows.old before clearing it out.

  • I know how to remove the folder. What I asked was if it can be created after the anniversary update (you answered) are important files (game saves etc.) generally stored there? – user598527 Aug 13 '16 at 7:51
  • @user598527 - You should look at the contents before you remove it using the cleanup tool. – Ramhound Aug 13 '16 at 10:07
  • Take a note that the condition in the w32sh's answer - "cleanmgr.exe - run as administrator" - is important. At first I tried to run cleanmgr as a regular user, and it didn't list Windows installation files and Windows previous version files as options for clean-up. – perlexed Sep 25 '16 at 8:07

I'll add a couple details since the other answer is missing them:

  • Yes the Anniversary Update causes a Windows.old folder to be created. These folders will be created whenever you update to a new "major version" of Windows that you may want to rollback from. If I recall correctly, the last update before the AU that created such a folder was the Threshold 2 update.

  • You actually only have 10 days to roll back this one; not a month.

  • I believe the folders only contain important system files that have changed since the last major update. If you don't plan on rolling back, it should be able to be safely deleted. I'd poke around it first if I were you since it's been awhile since I looked in mine. If it's just the typical contents of the "windows" folder, you should be safe. If it contains a "users" or "documents and settings" folder, I'd go through them.

I just checked my windows.old folder, and it appears that it's a copy of the structure of the root of the drive. It contains "users" and "program files" folders, but all the subfolders of "users" are empty, and the copied program files appear to all be Windows related programs. Considering the copied "users" folder is only 107mb (compared to the actual "users" folder that's 16.8gb), it seems to be a fairly superficial copy, so it should be safe to delete. It would also barely take up any space if you wanted to make a backup of just that folder.

  • I browsed through the folder contents too and it indeed looks like only system files are stored there. I backed up Program Files and user folder just in case. The only program I've found so far that lost saved settings is Nvidia Control Panel, but being driver software I don't find that surprising. The program doesn't store its config files anywhere nor there's a way to export. – user598527 Aug 13 '16 at 14:14

For anyone else reading this... do not be tempted to manually clear out this folder using takeown and deletion. In my experience, it contains "links" from Windows.old to other areas of your system.

  • Is using the Disk Cleanup tool safe? – user598527 Aug 13 '16 at 14:17
  • 2
    @user598527 Yes, I've cleared the windows.old folder twice using the cleanup tool. No issues. – Carcigenicate Aug 13 '16 at 14:21

I browsed through the Windows.oldfolder content and it looks like that only system files are stored there. The only program I've found so far that lost saved settings is Nvidia control panel, but being driver software I don't find that surprising. The program doesn't store its config files anywhere nor there's a way to export as far as I know.

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