Description of the Windows Update Standalone Installer in Windows

Introduction

This article describes the Windows Update Standalone Installer (Wusa.exe) in the following Windows operating systems:

Windows Server 2008

Windows Server 2008 R2

Windows Server 2012

Windows Server 2012 R2

Windows Server 2016 Technical Preview

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.

More Information

An .msu file contains the following contents.

Windows Update metadata

Describes each update package that the .msu file contains.

One or more .cab files

Each .cab file represents one update.

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:

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.

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:

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

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

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

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

You can use Wusa.exe to uninstall an update in Windows 7, Windows Server 2008 R2, Windows 8, and Windows Server 2012.

Note You cannot use Wusa.exe to uninstall updates in Windows Vista or Windows Server 2008. You can use Windows Defender Software Explorer to manually uninstall the updates. For more information about Software Explorer, go to the following Microsoft website:

Using Software Explorer in Windows Defender
You can use the following switches together with Wusa.exe.

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.

Prevents Wusa.exe from restarting the computer. The /norestart switch is ignored if the /quiet switch is not present. If you run Wusa.exe together with these two switches, you must manually restart the operating system after the installation is complete if the installation requires you to restart the computer.

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 /quiet /norestart

Uninstalls the specified package or KB number.

Specifies the package to be uninstalled by using its KB number. Can be passed only together with the /uninstall switch.

Wusa.exe extracts the package contents to a destination folder.

When this switch is combined with the /quiet switch, Wusa.exe prompts you before it begins a restart for install and uninstall operations.

When this switch is combined with the /quiet switch, Wusa.exe forcibly closes applications and then begins a restart.

Note The .msu files can be installed to an offline image by using the DISM.exe /Add-Package option together with the Windows 7 or Windows 8 OEM Preinstallation Kit (OPK) or the Windows Automated Installation Kit (AIK). For more information, go to the following Microsoft TechNet website:

Operating System Package Servicing Command-Line Options
To view the Windows Update Standalone Installer event log, follow these steps:

Click Start , type event viewer in the Start Search box, and then click Event Viewer in the Programs list. In Windows 8 and Windows Server 2012, on the Start screen, type event viewer, click Settings, and then click View event logs under Settings.

If you are prompted for an administrator password or for confirmation, type the password, or click Continue.

In Event Viewer, expand Windows Logs, and then click Setup.

Setup events appear in the middle pane.

In the Actions pane, click Filter Current Log.

In the Event sources list, click to select the WUSA check box, and then click OK.

References

For more information about the Windows Update Agent API, go to the following Microsoft website:

Windows Update: FAQ

Note: If you’re looking for Microsoft Office update info, see Install Office updates.

In Windows 10, you decide when and how to get the latest updates to keep your device running smoothly and securely. When you update, you’ll get the latest fixes and security improvements, helping your device run efficiently and stay protected. In most cases, restarting your device completes the update. Make sure your device is plugged in when you know updates will be installed.

If other questions come up when you update Windows 10, here are some other areas that might interest you:

When you only want info about updating Windows 10, you’ll find answers to many of your questions here:

When the Windows 10 May 2020 Update is ready for your device, it will be available to download and install from the Windows Update page in Settings. Choose a time that works best for you to download the update. You’ll then need to restart your device and complete the installation. After that, your device will be running Windows 10, version 2004.

To manually check for the latest recommended updates, select Start > Settings > Update & Security > Windows Update > Windows Update .

To get help updating to the latest version of Windows 10, go to the Microsoft software download page and download the Update Assistant.

Some updates may not be available on all devices at the same time—we’re making sure updates are ready and compatible.

To stay up to date, select Start > Settings > Update & Security > Windows Update > Windows Update , and then select Check for updates.

If a feature update is available for your device, it will appear separately on the Windows Update page. To install it, select Download and install now.

Here are a few things you can try if you’re having trouble installing updates:

Make sure that your device is connected to the internet. Downloading updates requires an internet connection.

If you’re connected the internet, try to install the updates manually. Select Start > Settings > Update & Security > Windows Update > Windows Update , and then view available updates.
Check for updates

Run the Windows Update Troubleshooter. Select Start > Settings > Update & Security > Troubleshoot . Under Get up and running, select Windows Update.

The time required to download updates primarily depends on internet connection speed, network settings, and update size. Make sure your device is plugged in and connected to the internet to download updates faster.

You can’t stop updates entirely—because they help keep your device safe and secure, updates will eventually need to be installed and downloaded, regardless of your update settings. Here’s how to temporarily pause updates from being downloaded and installed. Note that after the pause limit is reached, you’ll need to install the latest updates before you can pause updates again.

In the Windows 10 November 2019 Update (version 1909) or later, or in Windows version 1809 for Pro or Enterprise, select Start > Settings > Update & Security > Windows Update . Then choose one of the following options:

Select Pause updates for 7 days.

Select Advanced options. Then, in the Pause updates section, select the drop-down menu and specify a date for updates to resume.

To finish installing an update, your device will need to restart. Windows will try to restart your device when you’re not using it. If it can’t, you’ll be asked to schedule the restart for a more convenient time. Or, you can schedule anytime by following these steps:

Select Start > Settings > Update & Security > Windows Update > Windows Update .

Select Schedule the restart and choose a time that’s convenient for you.

You can set active hours to make sure automatic restarts for updates only happen when you’re not using your device. Learn about active hours for Windows 10.

Try deleting files you don’t need, uninstalling apps you don’t use, or moving files to another drive like an external USB drive or OneDrive. For more tips on freeing up disk space, see Free up drive space in Windows 10.

We recommend keeping devices like laptops and tablets plugged in when you’re not using them. This way, if updates are installed outside active hours, your device will have enough power to complete the installation. Windows updates don’t consume more battery than other typical system processes.

An update history is available so you can see which updates were installed, and when. You can also use this list to remove specific updates, although we don’t recommend this unless it’s necessary.

Select Start > Settings > Update & Security > Windows Update > Windows Update > View update history .

For more info about what’s included in updates for Windows 10, see Windows 10 update history.

We don’t recommend that you remove any installed updates. However, if you must remove an update, you can do so in update history.

Select Start > Settings > Update & Security > Windows Update > View update history > Uninstall updates.

Select the update you want to remove, then select Uninstall.

Feature updates are typically released twice per year and include new functionality and capabilities as well as potential fixes and security updates. Quality updates are more frequent and mainly include small fixes and security updates. Windows is designed to deliver both kinds of updates to devices through Windows Update.

To double check that your device is up to date, open Settings > Update & Security > Windows Update and see your update status and available updates.

To find which version of Windows you’re running, see Which version of Windows operating system am I running?

Reserved storage is not automatically turned on by Windows in any update scenarios. It is only turned on for new devices with the Windows 10 May 2019 Update (version 1903) or later preinstalled, or devices on which a clean install was performed.

Note: If you’re looking for Microsoft Office update info, see Install Office updates.

The best way to keep Windows 8.1 up to date is to turn on automatic updates. With automatic updates, you don’t have to search for updates online or worry about missing critical fixes or device drivers for your PC. Instead, Windows Update automatically installs important updates as they become available.

To turn on automatic updates:

Open Windows Update by swiping in from the right edge of the screen (or, if you’re using a mouse, pointing to the lower-right corner of the screen and moving the mouse pointer up), select Settings > Change PC settings > Update and recovery > Windows Update. If you want to check for updates manually, select Check now.

Select Choose how updates get installed, and then, under Important updates, select Install updates automatically (recommended).

Under Recommended updates, select Give me recommended updates the same way I receive important updates.

Under Microsoft Update, select Give me updates for other Microsoft products when I update Windows, and then select Apply.

Click the questions below to see answers about how Windows Update keeps your device up to date.

Note: If your PC is connected to a network where updates are managed by Group Policy, you might not be able to change settings related to Windows Update. For more info, contact your organization’s technical support.

Open Windows Update by swiping in from the right edge of the screen (or, if you’re using a mouse, pointing to the lower-right corner of the screen and moving the mouse pointer up), select Settings > Change PC settings > Update and recovery > Windows Update. To check for updates manually, select Check now.

An update history is available so you can see which updates were installed, and when. You can also use this list to remove specific updates, although we don’t recommend this unless it’s necessary.

To see your PC’s update history, open Windows Update by swiping in from the right edge of the screen (or, if you’re using a mouse, pointing to the lower-right corner of the screen and moving the mouse pointer up), select Settings > Change PC settings > Update and recovery > Windows Update > View your update history.

We don’t recommend that you remove any installed updates. However, if you must remove an update, you can do so in update history.

Open Windows Update by swiping in from the right edge of the screen (or, if you’re using a mouse, pointing to the lower-right corner of the screen and moving the mouse pointer up), select Settings > Change PC settings > Update and recovery > Windows Update > View your update history.

Select the update you want to remove, then select Uninstall.

Here are a few things to try if you’re having problems installing updates:

Make sure that your PC is connected to the internet. Some updates can’t be installed if you’re using a metered internet connection.

If you’re connected the internet and updates aren’t installed automatically, wait a few minutes and then try to install the updates manually.

See the Fix Windows Update errors guided walkthrough to try to fix the problem.

Support for Windows 7 ended on January 14, 2020

We recommend you move to a Windows 10 PC to continue to receive security updates from Microsoft.

Click the questions below to see answers about how Windows Update keeps your device up to date.