MSU Files Explained: How to Download, Install, and Manage Windows Updates

Written by Alex Marin · May 23rd, 2024

It is important to ensure that your Windows operating system is kept up to date in this age of technology. It is a matter that leads us to Microsoft Update Standalone Packages (MSU files), an essential element in the updating process of Windows.

This complete guide aims at demystifying MSU files by providing insights on downloading, opening, and installing them as well as managing these operations silently and without immediate restarts.

We will also look at the differences between MSU and CAB files and briefly touch on using the Windows Update Standalone Installer (WUSA.exe) for managing MSU files.

What is an MSU File?

An MSU file can be described as a package used by Microsoft Windows for the distribution of updates to the operating system.

These include such details about each update as its description, applicable installation rules, etc., making it an all-inclusive solution for distributing Windows updates where every package has everything needed for successful update procedures.

Downloading MSU Windows Update Files

To download MSU files, users typically visit the Microsoft Update Catalog website, a repository of updates where you can search for and download individual updates for Windows.

Direct access to MSU files for various versions of Windows is provided by the Update Catalog either when you are dealing with a specific security flaw or updating a system manually. To start the process, just click on the “Download” button once you have identified the required update.

Opening MSU Files

Opening an MSU file is easy because it was designed to be double-clicked and run directly on Windows. Once executed, the Windows Update Standalone Installer (WUSA) takes over to guide users through the installation procedure. This simplicity makes it possible for users to apply updates easily without having to go through complicated steps or use extra software.

MSU vs. CAB Files: Understanding the Difference

The main distinction between MSU and CAB files comes in terms of their intended usage and format.

MSU files are standalone update packages that come along with metadata and they are specifically meant for updating different aspects of Windows.

On the other hand, CAB (Cabinet) files act as general-purpose containers used to store compressed files which may be utilized for different purposes such as Windows updates among others.

Normally, CAB files need additional instructions or scripts so that they can be installed unlike MSUs are self-contained and hence can directly be managed by WUSA.

Silent Installation of MSU Files

One of the most powerful features of MSU files and WUSA is the ability to perform silent installations, allowing updates to be applied without user interaction and without forcing a system reboot.

This can be incredibly useful for IT administrators managing multiple machines or for users who wish to update without interruption.

To install an MSU file silently, you can use the following command line in an elevated Command Prompt:

wusa.exe "path\to\update.msu" /quiet /norestart

This command tells WUSA to install the specified MSU file quietly (`/quiet`) and to avoid restarting the system afterward (`/norestart`), making it ideal for batch processing or scripts.

WUSA: A Closer Look

The Windows Update Standalone Installer (WUSA) is a utility built into Windows that facilitates the installation and uninstallation of updates packaged in MSU files.

It's designed to integrate seamlessly with Windows Update services, ensuring that updates are applied correctly and efficiently. While its interface is simple, the underlying functionality of WUSA is robust, supporting various command-line options for tailored update management.

Uninstalling MSU Files with WUSA

In some cases, an update may need to be rolled back. WUSA also supports the uninstallation of previously installed MSU files using a command similar to the installation process. To uninstall an MSU file, you can use the following command:

wusa.exe /uninstall /kb:123456 /quiet /norestart

Here, `/kb:123456` should be replaced with the KB number of the update you wish to uninstall.

This command performs the uninstallation silently and prevents an immediate restart, mirroring the convenience and control offered during the installation process.

MSU Files and Advanced Installer

Incorporating a Windows Update into your installation package as a pre-installation requirement is easy and simple with the Prerequisites view in Advanced Installer. This is how you can smoothly add it:

  • Bundled Prerequisite Software: To add “Package Prerequisite” click on the button on the toolbar, right-click on it and choose “New Package Prerequisite”, or just use the Insert key; this will invoke an Open dialog box to let you browse for setup files of such prerequisite.
  • Downloadable Prerequisite Software: Select URL Prerequisite from the toolbar or New URL Prerequisite from the context menu; thus define a URL where it could be downloaded.

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It's important to remember that prerequisites added this way come with default settings initially. You'll need to manually configure them—for example, by defining the correct installation conditions for your prerequisite in the prerequisite's installation conditions tab.

In the Install Conditions tab, you should specify which Windows versions are supported by the Windows Update.

Go to the Install Conditions section and select the "Install Prerequisite based on conditions" option.

To set up the search criteria for the prerequisite, proceed as follows:

  1. Criteria: Opt for a search conducted by a custom executable.
  2. Executable Selection: When prompted, navigate to and select CMD.exe located in C:\Windows\System32\.
  3. Argument Configuration: Use the argument `/c "wmic qfe get hotfixid | findstr ^"KB id^""` to define your search parameter.
install conditions tab

This configuration leverages the Windows Management Instrumentation Command-line (WMIC) for a swift and straightforward method to identify if the specific hotfix, identified by its KB ID, is already installed on the system.

The command `wmic qfe get hotfixid` efficiently lists all the hotfix IDs installed on the local machine, making it an invaluable tool for verifying pre-installation prerequisites.

Conclusion

MSU files and the Windows Update Standalone Installer are the vital components in the Windows ecosystem that manage system updates.

Precision and flexibility are guaranteed by MSU files and the Windows Update Standalone Installer.

They can be obtained from Microsoft’s update directory or through silent installation/uninstallation command lines for MSU files, which guarantees a more dependable approach to maintaining Windows systems.

These tools help users and administrators keep their systems safe, updated, and running at peak performance by using them fully.

Written by
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Alex Marin

Application Packaging and SCCM Deployments specialist, solutions finder, Technical Writer at Advanced Installer.

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