Windows.old on cleaninstall ?

Sounds to me like you may have done a custom install. Custom Install Windows 11

THIS is a true clean install Clean Install Windows 11

During the install process, Delete ALL partitions and install windows on unallocated space.
I did one yesterday for 25h2 for a friend and no windows.old was created.

glasskuter said:

Sounds to me like you may have done a custom install. Custom Install Windows 11

THIS is a true clean install Clean Install Windows 11

During the install process, Delete ALL partitions and install windows on unallocated space.
I did one yesterday for 25h2 for a friend and no windows.old was created.

Click to expand...

I think earlier, people were saying it depended which installer you used during the clean install Did you use the original installer, like I did (and I didn't get a Windows Old folder). Apparently it's the new installer that creates an empty windows old folder.

Megahertz said:

It seems you didn't booted from the Win 11 USB installation drive and deleted ALL previous Windows partitions (EFI, MSR, C: and Recovery) and pointed to install on the unallocated space.

You will have a Windows.old folder if you didn't delete the Windows partitions and pointed to install on the C: partition.

Click to expand...

They stated that it was a new unformatted drive.

Most of us, with some experience, never had seen a clean install creating a Windows.old folder.
MS just created something useless for a reason they may not even know the answer or is just a bug that will be corrected in the future.

Hazel123 said:

Did you use the original installer

Click to expand...

Sure did. Thanks

What is the Windows.old folder?
• It’s a backup of your previous Windows installation, including system files, user profiles, installed programs, and settings.
• Windows Setup creates it automatically when it detects an existing Windows installation on the drive you're installing to.

Why does it appear during a “clean install”?
• If you don’t format the system partition before installing Windows, Setup treats it as an upgrade or reinstallation, not a full wipe.
• Even if you boot from installation media and choose “Custom Install,” skipping the format step means Windows will preserve the old OS in Windows.old.

How to avoid it?
• To ensure a truly clean install without Windows.old, you need to:
1. Boot from installation media (USB/DVD).
2. Choose “Custom: Install Windows only.”
3. Delete or format the existing Windows partition before proceeding.

Source: CoPilot

What does copilot say about the difference between the new installer and the old installer?

Hazel123 said:

What does copilot say about the difference between the new installer and the old installer?

Click to expand...

Ask it and see what it says.

cereberus said:

The simplest way to avoid this sillyness is to use the old installer, not the new one.

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Of course, you could always just embrace unattended setup and script the deletion of the windows.old folder automagically
. Just one more reason I like unattended setups.

Before I go any further, yes, I get that this is not a solution for the average user. In fact, it is definitely NOT something that someone who rarely installs Windows would want to use because it is way overkill. Like trying to swat a fly with an atomic bomb.

But for those who install Windows often, for example, for testing purposes, unattended setup is a true game changer.

For example, I have one answer file that I have been recycling for several years. I only make minor mods now and then such as to fix stuff that did not work with the new Windows setup, or to add a capability like bypassing the installation of quality updates during setup. But once you have an unattended setup file that you like, maintenance is rare and easy.

So many issues can be addressed in one fell swoop with unattended setup. For example:

Install Windows completely hands free
Bypass checks for unsupported hardware
Partition and configure the disks in your system EXACTLY how YOU want them, not what Windows setup defaults to
Create a local user account
Bypass check for quality updates during setup
Install all drivers for the system so that no drivers need to be installed after setup
Prevent automatic device encryption
Delete the windows.old folder

This is just a small subset of what can be done with unattended setup. In fact, I feel like half the topics on this forum such as the weeping over Windows forcing the use of a local account or automatically enabling device encryption are just non-issues for me. Most of the time I don't even bother reading those posts because the issues they discuss just don't affect me at all.

Again, not for the occasional installer of Windows. I install Windows several times per day, so unattended setup is a no brainer for me.

This is what Chat GPT says about the difference between the old and new installers - just out of interest. Is it correct (asking the experts here!)?

Hello! The difference between the Windows 11 24H2 "new installer" and the old installer primarily comes down to how the installation process is handled under the hood, how modernized the setup experience is, and compatibility with newer technologies and hardware. Here's a breakdown:

---

Summary of Differences:​

New Installer (Windows 11 24H2)​

Highlights:​

• Based on Unified Update Platform (UUP):
  • Reduces size by combining update and installation methods.
  • Designed for streamlined OTA updates and clean installs using the same files.
• Optimized for modern hardware:
  • Especially relevant for Copilot+ PCs and ARM64 devices (like Snapdragon X).
• Cloud-centric design:
  • Better integration with Microsoft services during setup.
• Reduced dependency on legacy components:
  • Less support for old drivers or legacy BIOS systems.
  • Drops support for older CPUs officially.

Downsides:​

• Less mature — might have fewer customization options.
• May drop support for older scripting tools used in enterprise deployment.
• Requires TPM 2.0 and Secure Boot — cannot bypass checks easily.

---

Old Installer (Legacy Setup)​

Highlights:​

• Based on traditional WinPE-based setup that’s been used since Windows Vista/7.
• Uses a large install.wim or install.esd file.
• Supports legacy BIOS and a broader range of hardware.
• Compatible with traditional tools (DISM, answer files, image servicing, etc.).
• More flexibility for power users and IT departments.

Downsides:​

• Larger footprint.
• Slower install/update process.
• More prone to legacy driver issues or incompatibilities.
• Eventually being phased out.

Why Microsoft is Shifting to the New Installer​

• To simplify updates across versions and platforms.
• To unify mobile, desktop, and cloud deployment strategies.
• To improve performance, especially on ARM and future hardware.
• To support AI-enabled features in Copilot+ PCs and other new lines.

---

Final Thoughts:​

• If you're using modern hardware and want future-proof installation, the new installer is the way to go.
• If you need flexibility, compatibility with older devices, or are building custom Windows installs, the old installer may still be preferable for now.
• For now, Microsoft offers both options, but the new installer will likely become the default in future versions beyond 24H2.

Marcus Vinicus said:

Ask it and see what it says.

Click to expand...

I have it uninstalled I prefer Chat GPT if using any AI at all.

Chat GPT says the creation of the Windows old folder in the new installer is a bug.

The creation of an empty Windows.old folder during a clean install using the new Windows 11 24H2 installer is a known quirk, and it’s worth breaking down what’s happening here and why it's different from the old installer.

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Windows.old Folder Behavior in Clean Installs​

New Installer (24H2)​

• Creates an empty Windows.old folder, even during a true clean install.
• This folder is typically 0 bytes, or contains minimal metadata.
• Appears to be a bug or leftover behavior from the UUP-based deployment method (Unified Update Platform).
• In theory, Windows.old is meant to store the previous OS during upgrades, allowing rollback.
• With the new UUP-based installer, Microsoft may be using the same engine/path for upgrades and clean installs, and it doesn't differentiate perfectly between them.
• That’s likely why the placeholder folder appears — the installer is preparing for an upgrade rollback scenario, but never populates it because it's a clean install.

Old Installer

• Clean installs do not create a Windows.old folder, as expected.
• Windows.old is only created during:
  
  • Feature updates (e.g., 23H2 → 24H2).
  • Upgrades from older versions (e.g., Windows 10 → 11).
• The old installer explicitly detects clean install scenarios and skips creating this folder.

---

Why This Matters (Or Doesn’t)​

• Functionally, the empty Windows.old does nothing and can be safely deleted.
• It does not consume disk space, unless populated (which it isn’t in clean installs).
• Could be seen as sloppy or untidy from a system maintenance perspective.
• Might confuse users expecting a clean install to have no remnants of other installations.

Thanks all it have to do with the new installer I no now, maybe it's the back function in the installer to set your settings and apps back from another computer. The empty windows.old directory is easy to remove so I did that.

It took me some time when using 24H2 ISO to realize that this is a new installation method that is similar to an upgrade but not a real upgrade. I thought I had made a mistake in the clean installation steps that I know.

I did also a clean install on my laptop with a brandnew nvme ssd 1TB with the new official Windows installer. Here I also get the windows.old. But also the windows security centre in a wrong language!! Also bitlocker is running on all the drives not only the C drive. I think I install first an old version and than do the upgrade to 25H2.

Cameraman1955 said:

I did also a clean install on my laptop with a brandnew nvme ssd 1TB with the new official Windows installer. Here I also get the windows.old. But also the windows security centre in a wrong language!! Also bitlocker is running on all the drives not only the C drive.

Click to expand...

That is device encryption a cut down version of bitlocker. It is a bit misleading but itviscnot actually active yet but ready tovbe active. Just enable it, then disable it from the device encryption menus.

Re. security centre, no idea.

Someone else mentioned that Security Center is in English upon the initial installation. When I tested it on a French ISO, Security Center flipped to French after doing the first Windows updates (security/Defender things).