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Cached msi files under installer folder

Tarek Elsharkawi 20 Reputation points
2026-05-19T12:22:45.6866667+00:00

Hello

How can I automatically clear the installer folder from the msi cached files that it takes more than 100 GB

Windows for business | Windows Client for IT Pros | User experience | Other

Answer accepted by question author

Domic Vo 24,130 Reputation points Independent Advisor
2026-05-19T13:01:00.8933333+00:00

Hi Tarek Elsharkawi,

The massive size of your C:\Windows\Installer folder is not a Windows bug, but rather a known behavior of the Windows Installer service accumulating orphaned patch files over time. This directory is a critical system repository that holds the setup files required to update, repair, or uninstall the applications currently on your machine. Forcibly deleting the contents of this folder will corrupt your software environment and prevent future updates, but you absolutely do not need to reinstall Windows to reclaim your storage space. The extreme bloat is usually caused by older third-party applications failing to deregister and remove their temporary files during uninstallation.

Microsoft does not include this directory in the standard Disk Cleanup utility because the risk of accidentally breaking active software is too high. The safest method to resolve this involves cross-referencing the registered applications listed in your system registry at HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Installer\UserData against the physical files in the folder. Files not found in that registry key are orphaned and can be safely removed. While there is no native one-click button for this, IT professionals typically use widely available community PowerShell scripts to automatically compare that registry path with the folder contents, safely moving the unregistered files to a backup drive before final deletion. You can also utilize the official Microsoft Program Install and Uninstall Troubleshooter to safely clean up specific corrupted application registry entries holding onto old cache files.

Hope this answer brought you some useful information. If it did, please hit “accept answer”. Thank you :)

Domic V.

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  1. AI answer

    2026-05-19T12:22:59.9233333+00:00

    The Windows Installer cache folder (%windir%\Installer, typically C:\Windows\Installer) must not be automatically cleared. The .msi and .msp files stored there are required for repairing, updating, and uninstalling applications that were installed with Windows Installer. These cached files are unique per machine and cannot be safely regenerated or copied from another computer.

    If files are deleted from this cache, problems can occur later when trying to uninstall, repair, or update software such as SQL Server, Office, or other MSI-based applications. In many cases, if the cache is damaged or missing, the only supported fix is to rebuild the operating system and reinstall the affected applications.

    Because of this, there is no supported or recommended method or tool from Microsoft to automatically clean or purge the Windows Installer cache to reclaim disk space.

    If the folder is consuming excessive space, the supported options are:

    1. Identify and remove unneeded applications via normal uninstall methods (Apps & Features / Programs and Features). This may indirectly reduce future cache growth but will not safely delete arbitrary cache files.
    2. If specific products (for example SQL Server, Office, or others) are known to be causing issues due to missing cache files, follow that product’s documented recovery steps or contact the vendor. For SQL Server, there is specific guidance on restoring missing cache files; for other applications, the vendor may require a full OS rebuild and reinstall.

    Do not script or automate deletion of files under C:\Windows\Installer.

    References:

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