Why is 24H2 creating a Windows.old folder after doing a complete format to the system?

As soon as I began using 24H2 media creation to install Windows after formatting my drive and doing a fresh OS install, 24H2 keeps creating a Windows.old folder, this never happened when using older versions of Windows 11 (pre 24H2), why is this folder being created after completely wiping out my drive?

You’re not alone, it seems to be a 24H2 thing with clean installs. I can’t tell you if it will cease to happen in the future or if Microsoft wants this by design

I can only guess that this is caused by the new 24H2 install process where Windows will be updated to the latest build during a clean install. So if you clean install with ISO build 1742, Windows will update you to the latest build during the install process.
This is most likely the reason for the Windows.old folder, I assume.

antspants said:

I can only guess that this is caused by the new 24H2 install process where Windows will be updated to the latest build during a clean install. So if you clean install with ISO build 1742, Windows will update you to the latest build during the install process.
This is most likely the reason for the Windows.old folder, I assume.

Click to expand...

antspants said:

You’re not alone, it seems to be a 24H2 thing with clean installs. I can’t tell you if it will cease to happen in the future or if Microsoft wants this by design

Click to expand...

Do you ever answer with just one post?

Windows.old folder is typically used for restore purposes and usually sits there for about 10 days after the installation or the update.
It can be deleted before those ten or so days using Disk cleanup & other means.

This is not new to 24H2.

You have to actually delete the partitions so space is unallocated. Then it does not create a windows.old.

cereberus said:

This is not new to 24H2.

You have to actually delete the partitions so space is unallocated. Then it does not create a windows.old.

Click to expand...

I literally secure erased the SSD and ran "clean all" with diskpart and it still creates this folder.

This is a new change to 24H2 clean installs, it's following an "upgrade" process even though it knows a clean install is happening. You will always get an empty Windows.old folder, even if you wiped the disk. A different setup client is running which does the work. If you're running a manual install, Setup will eventually offer you an on-screen link to revert to the old-style setup.exe.

MS has offered no explanation or guidance on why it needs to be different. You will also get a mandatory Windows Update screen at the end of OOBE, to force update your Windows before you're allowed to logon.

garlin said:

This is a new change to 24H2 clean installs, it's following an "upgrade" process even though it knows a clean install is happening. You will always get an empty Windows.old folder, even if you wiped the disk. A different setup client is running which does the work. If you're running a manual install, Setup will eventually offer you an on-screen link to revert to the old-style setup.exe.

MS has offered no explanation or guidance on why it needs to be different. You will also get a mandatory Windows Update screen at the end of OOBE, to force update your Windows before you're allowed to logon.d

Click to expand...

Well, I have just tested it on a clean install on a 24H2 VHDX I clean installed to a few days ago. I had to use the previous installer on 3rd page of installer, as there is a bug using the ridiculous new installer installing to a vhdx file.

On very first page, I pressed shift+f10 to get to command, and ran diskpart, attached vhdx file and it had all windows files.
I then did a "clean all", and exited diskpart.

I carried on and installed to the vhdx file (all unallocated space), and clean installed 24h2 (creating local account with oobe\bypassnro method).

It worked perfectly and no sign of a windows.old folder.

As you say, this is probably an artifact of the new installer.

One irritating aspect also of the new installer is the new oobe update screen which forces the cumulative updates, as you say. This can take ages depending on internet and drive type (easily up to 30 minutes or more). This is a terrible move - previously we could oobe on version on usb drive, do the initial configurations, and then use WU to get cumulative updates.

Fortunately, we still have the previous installer. Even if MS stupidly remove option for old installer, there are at least two options:

1) use 23h2 installer replacing install.wim and boot.wim in sources folder with 24h2 versions.

2) use dism to install 24h2.

Make sure you feed back to MS how crap the new installer is!

You’re all late to the party.

Mine didn't create/save a Windows.old folder but I wiped the drive completely yesterday [outside of Windows] and chose Not to save anything during the install.

As was mentioned "This is a new change to 24H2 clean installs", so is the automatic Bitlocker on the system drive but no clue given of any password for it.


Did get a new folder.

antspants said:

You’re all late to the party.

Click to expand...

We have discussed this partly before but not (iirc) about blank windows.old.

So we have been at party all along and still grooving.

cereberus said:

We have discussed this partly before but not (iirc) about blank windows.old.

So we have been at party all along and still grooving.

Click to expand...

Your ignore function isn’t working.

antspants said:

Your ignore function isn’t working.

Click to expand...

Only because I changed my mind.

Open administrative command prompt and copy and paste > post a share link

dism /online /Get-OSUninstallWindow


What is the size of the windows.old?

Windows.old is always empty. Nothing gets created in the folder, but it has to exist in order for the "upgrade" workflow to run.

It's been covered before, if you run Process Explorer from WinPE -- 24H2's setup.exe is calling SetupPrep.exe (which does the actual install). SetupPrep.exe is normally used for in-place upgrades.