Msizap Overview

Applies To: Windows Server 2003, Windows Server 2003 R2, Windows Server 2003 with SP1, Windows Server 2003 with SP2

Msizap.exe: Windows Installer Zapper

This command-line tool deletes configuration data that Windows Installer maintains for products that it installs, including the directories, files, registry subkeys, and registry entries in which Windows Installer stores configuration data. You can use Msizap to remove remnants of corrupted Windows Installer installations that prevent you from installing a product correctly.

You can also use Msizap to give administrators Full Control permissions to Windows Installer folders, files, and registry subkeys.


  • Msizap can delete installation data that is required by the system. Products installed by Windows Installer might not operate properly after using this tool.

    Msizap is designed as a last resort tool to be used only when conventional methods of repairing or removing an installation have failed. Before using Msizap, use Add or Remove Programs to remove or repair the installation. If that fails, use the Msicuu Overview (Msicuu.exe), which runs Msizap, but prevents you from causing unnecessary harm to the system.

You can use Msizap to correct the following installation failures.

  • A Windows Installer installation, uninstallation, or rollback is interrupted or fails unpredictably. Because the installation did not complete successfully, Windows Installer will not uninstall or reinstall the program, or install any another programs.

  • Registry entries for a product have been deleted or changed, damaging the operation of the products and preventing you from uninstalling or reinstalling the product.

  • Multiple instances of a setup program are running simultaneously, or an instance of a setup program cannot run.

Corresponding UI

There is no corresponding user interface for this tool.


Windows Installer manages the installation and removal of applications on Windows XP Professional and Windows Server 2003 operating systems. Typically, these installations conclude successfully, or are successfully reversed ("rolled back") or repaired. However, in rare situations, an installation, a rollback, or an uninstallation fails, leaving installation files and registry entries that would otherwise be removed. As long as these objects remain on the system, Windows Installer considers the installation to be active and incomplete.

Because Windows Installer conducts only one installation at a time, it will not start another installation until all indicators of the active installation are removed.

You can use Msizap to remove particular installation remnants, such as the InProgress registry subkey and the rollback registry data. You can also delete all configuration data for a specified installation, or all Windows Installer installations on the system.

System Requirements

  • This version of Msizap runs on Windows XP Professional and Windows Server 2003 operating systems. (Windows 2000 includes a version of Msizap for that operating system.)

  • The user must be a member of the Administrators group on the computer affected.

  • Msizap affects only the local computer. You cannot use it to manage a remote computer.

File Required

  • Msizap.exe

See Also


Msizap Remarks
Msizap Syntax
Msizap Examples
Alphabetical List of Tools
Windiff Overview
Remote Overview
Poolmon Overview
Msizap Overview
Msicuu Overview
Memsnap Overview
Devcon Overview