Config.Msi C:\Config.Msi

Hidden temporary Windows Installer folder: rollback files created during an MSI installation or uninstallation.

Updated on 12 November 2026 By AltF4 Formation

What it’s for

Config.Msi is the hidden folder where Windows Installer writes rollback information while installing, updating or uninstalling an MSI package. If the operation fails or is canceled, the service uses it to put the system back in its earlier state.

What it contains

During an operation: rollback scripts (.rbs), backup files (.rbf) and temporary copies of files. After a successful operation the folder is normally removed or emptied. Leftover content usually means an installation was cut short by a forced restart or a crash.

Risks and best practices

Deleted during an installation (msiexec active, Windows Update working, restart pending), it makes rollback impossible and can leave a product half-installed.
A leftover with no installation running and no restart pending can be deleted by an administrator. Check first that msiexec is not running.
A folder that grows again with every operation points to a repeating failure. Look at the Application log and the MSI logs.

Useful commands

# Contents (hidden folder)
Get-ChildItem "$env:SystemDrive\Config.Msi" -Force -ErrorAction SilentlyContinue | Select-Object Name, Length, LastWriteTime

# Is an MSI installation running?
Get-Process -Name msiexec -ErrorAction SilentlyContinue

# Latest Windows Installer events in the Application log
Get-WinEvent -FilterHashtable @{LogName='Application'; ProviderName='MsiInstaller'} -MaxEvents 15 |
    Select-Object TimeCreated, Id, Message

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