Why we have Windows.old recently out of the blue


Checking our computer we noticed a folder "Windows.old" dated just 10 days ago (Create date & modify date).  We know this folder is created when doing an upgrade, but we haven't done non to this computer, just the regular windows auto-updates.

Please advice on what could have caused it or how can we identify its origin?

Also, can we delete it? (it takes up 27.6gb exactly)
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janaAuthor Commented:
forgot to include, our computer is a Windows 10 Pro Version 10.0.16299.64.
William MillerIT SpecialistCommented:
Windows.old is created when a major update happens in Windows 10 (i.e Creators Update). It's put in place so you can roll back if you have issues and is cleaned out automatically every 30 days.

This was likely created during an automated update that installed new Windows features. This doesn't necessarily have to be an upgrade. It's safe to empty the folder only if you don't intend to roll the OS back to a previous build.

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Jose Gabriel Ortega CastroEE Rookie/Solution Guide/Topic Advisor and CEO Faru Bonon ITCommented:
Basically when you do the initial installation of windows.
It says that you need to download a newer version of windows (and there's an icon in the Update windows 'Windows10Update').

This update is actually a whole system update so your original installation is called "windows.old" and the new installation after the update is called "windows". Both are located in the System root folder. that's the main reason.
I installed my computer recently also windows 10 pro version and IU got it too:

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JohnBusiness Consultant (Owner)Commented:
As the others have pointed out, this happens with every version change (1607 and before to 1703 and 1709).  

Start in Safe Mode and run Disk Cleanup (system files) if you wish to remove before 30 days.

This will happen again in a few months.
Lee W, MVPTechnology and Business Process AdvisorCommented:
You can just use Disk Cleanup (NOT in safe mode) just click the "Cleanup System Files" option if you're satisfied you won't need to downgrade to the prior version.  No need to go in safe mode.
JohnBusiness Consultant (Owner)Commented:
It normally works in Normal Mode for me. But some people here have reported no, and Safe Mode always works. So try Normal and if not try Safe.
janaAuthor Commented:
Understood.  So if we decide no roll back is necessary, can we just right-click-delete on it? (Just like that or is there a recommended way?)
Jose Gabriel Ortega CastroEE Rookie/Solution Guide/Topic Advisor and CEO Faru Bonon ITCommented:
Use the System clean up. do not just right click and delete (it won't work)
JohnBusiness Consultant (Owner)Commented:
If you decide no roll back is necessary, use Disk Cleanup (better) and select Clean up system files. I have done this one lots.
JohnBusiness Consultant (Owner)Commented:
You are very welcome and I was happy to help.
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