Applies To
Windows Server 2012 Windows Server 2012 R2 Windows 10 Windows 10 Education, version 1607 Windows 10 Professional version 1607 Windows 10 Enterprise, version 1607 Windows 10 Enterprise version 1607 Windows 10 Enterprise, version 1809 Windows 10 Professional Education version 1607 Windows 10 Pro Education, version 1607 Windows Server 2019 Windows Server 2022 Windows 10 Home and Pro, version 21H2 Windows 10 Enterprise and Education, version 21H2 Windows 10 IoT Enterprise, version 21H2 Windows 10 Home and Pro, version 22H2 Windows 10 Enterprise Multi-Session, version 22H2 Windows 10 Enterprise and Education, version 22H2 Windows 10 IoT Enterprise, version 22H2 Windows 11 Home and Pro, version 21H2 Windows 11 Enterprise Multi-Session, version 21H2 Windows 11 Enterprise and Education, version 21H2 Windows 11 IoT Enterprise, version 21H2 Windows 11 Home and Pro, version 22H2 Windows 11 Enterprise Multi-Session, version 22H2 Windows 11 Enterprise and Education, version 22H2 Windows 11 IoT Enterprise, version 22H2 Azure Local, version 22H2 Windows 11 SE, version 23H2 Windows 11 Home and Pro, version 23H2 Windows 11 Enterprise and Education, version 23H2 Windows 11 Enterprise Multi-Session, version 23H2 DO_NOT_USE_Windows 11 IoT Enterprise, version 23H2 Windows 11 SE, version 24H2 Windows 11 Enterprise and Education, version 24H2 Windows 11 Enterprise Multi-Session, version 24H2 Windows 11 Home and Pro, version 24H2 Windows 11 IoT Enterprise, version 24H2 Windows Server, version 23H2 Windows Server 2025

Original publish date: March 2, 2017

KB ID: 934307

Change date

Description

June 26, 2025

  • Updated existing content and reformatted layout

  • Added the section "WUSA and Checkpoint cumulative updates"

In this article

Introduction

This article describes the Windows Update Standalone Installer (Wusa.exe) in supported versions of Windows operating systems.

The Wusa.exe file is in the %windir%\System32 folder. The Windows Update Standalone Installer uses the Windows Update Agent API to install update packages. Update packages have an .msu file name extension. The .msu file name extension is associated with the Windows Update Standalone Installer.

Contents of an .msu file

An .msu file contains the following contents.

Content

Description

Windows Update metadata

Describes each update package that the .msu file contains.  

One or more .cab files

Each .cab file represents one update.  

An .xml file

This .xml file describes the .msu update package. Wusa.exe uses the .xml file when you perform an unattended installation of the update by using the Package Manager tool (Pkgmgr.exe). For example, you download hotfix 934307. The Windows6.0-KB934307-x86.msu file is in the C:\934307 folder. You type the following command at a command prompt to expand the .msu file to a temporary folder:  

expand -f:* "C:\934307\Windows6.0-KB934307-x86.msu" %TEMP% Then, you type the following command at a command prompt:  

pkgmgr.exe /n:%TEMP%\Windows6.0-KB934307-x86.xml

A properties file

This file contains string properties that Wusa.exe uses. For example, this file contains the title of the associated article in the Microsoft Knowledge Base.

Use WUSA to install an update package

When you use Wusa.exe to install an update package, Wusa.exe expands the contents of the .msu file to a temporary folder. Then, Wusa.exe performs the following steps:

  1. Wusa.exe uses the Windows Update metadata in the .msu file to search for applicable updates.

  2. Wusa.exe copies the contents of the applicable updates to the Windows Update sandbox. The Windows Update sandbox is a protected folder.

  3. Wusa.exe calls the appropriate function in the Windows Update Agent API according to the mode in which you start Wusa.exe.

  4. When the Windows Update wizard finishes the installation, the Windows Update Agent API returns a status. Then, Wusa.exe works synchronously with the Windows Update Agent API.

Note Each update in an .msu update package is installed in a separate session. Only one instance of Wusa.exe runs when you use Wusa.exe. Wusa.exe does not change the contents of the updates in .msu files. The Windows Update infrastructure performs the required actions according to the contents of the update. When you start Wusa.exe in interactive mode, a welcome screen displays high-level information about the update. If you continue to install the update, Wusa.exe calls the appropriate function in the Windows Update Agent API to start the Windows Update wizard. The Windows Update wizard displays the Microsoft Software License Terms that are associated with the update package. Wusa.exe calls the Windows Update Agent API to continue the installation. Then, Wusa.exe waits until the Windows Update wizard finishes the installation. To install an .msu update package, run Wusa.exe together with the full path of the file. For example, if the Windows6.0-KB934307-x86.msu file is in the D:\934307 folder, type the following command at a command prompt to install the update package:

wusa.exe d:\934307\Windows6.0-KB934307-x86.msu

Note You can also double-click the .msu file to install the update package.

WUSA Switches

You can use the following switches together with Wusa.exe.

Switch

Description

/?, /h, /help

View help.  

/quiet

Run Wusa.exe in quiet mode without user interaction. When the tool runs in quiet mode, it runs without user interaction. The computer restarts if this is required. For example, if the Windows6.0-KB934307-x86.msu file is in the D:\934307 folder, type the following command at a command prompt to install the update package without user interaction:

wusa.exe d:\934307\Windows6.0-KB934307-x86.msu /quiet

Note When you use this switch, the Microsoft Software License Terms do not appear.