Over 60 GB of .msp files in C:\Windows\Installer

I have a Lenovo all-in-one desktop with a 500GB SSD. During my end-of-month backup, I noticed that the Macrium backup image was unusually large at 240GB.

Since all the data files on this computer are stored on a separate HDD, I used Wiztree to track down what was using up so much space. I discovered 561 files and 15 folders in C:\Windows\Installer.

Is there a safe way or a recommended program to clear out the unnecessary files in this folder?

For context, this Lenovo is not my daily driver. My main PC has significantly more programs installed, but it only has a few .msp files and takes up half the disk space.

msp files are related to patches.

There is software called patchcleaner that is supposed to safely clean out old files from the installer folder you no longer need but I have never used it.

I also second PatchCleaner.

Why not just delete the older folders that are empty as so many of mine are?

Copilot says: (it does say the empty Folders are OK to delete using File Explorer):

Those files are not safe to delete manually. Here’s the short, precise truth:

The contents of C:\Windows\Installer are required for repairing, updating, or uninstalling many programs. If you delete them, Windows Installer loses the cached packages it needs, and you can end up with:

• Programs that cannot uninstall
• Programs that cannot update
• Broken repair operations
• Orphaned entries in “Programs and Features”

Even very old files (2008, 2010, etc.) may still belong to software that is technically still installed or partially registered.

What​

You can safely remove only orphaned installer entries, but not by deleting the folder manually.

The correct, supported cleanup methods are:

1.​

This removes superseded installer packages created by Windows Updates.

2.​

Examples:

• PatchCleaner (identifies orphaned MSI/MSP files by checking Windows Installer registration)
• WICleanup.vbs (from Windows Installer SDK)

These tools compare the Installer folder against the actual Windows Installer database and only remove files that are truly orphaned.

3.​

Uninstalling programs through Settings will remove their associated MSI/MSP cache entries automatically.

Why the folder is so large​

Windows Installer caches:

• MSI (installer packages)
• MSP (patches)
• Transforms
• Rollback data

This is normal. A few hundred MB is typical; some systems exceed 1–2 GB.

Empty folders in C:\Windows\Installer are safe to delete. They’re leftovers from past installs and don’t affect Windows Installer. Open File Explorer and delete only the folders that show as completely empty.

Bottom line​

Do not delete C:\Windows\Installer manually. You can safely clean it only with tools that detect orphaned MSI/MSP files.

If you want, I can walk you through checking which files are orphaned and how to safely clean them without breaking anything.

skcusime said:

Is there a safe way or a recommended program to clear out the unnecessary files in this folder?

Click to expand...

pepanee said:

I also second PatchCleaner.

Click to expand...

It was not updated for a decade and I had issues, after using it.

I suggest to install a cleaner, a good one and clean this with it. Some cleaner such as Microsoft product are safe.

My installer folder is 1GB and I don't have a single *.msp file.