MSU File

What are MSU files and how to open them

Are you having problems opening a MSU file or just wondering what they contain? We explain what these files are used for and show you software that we know can open or otherwise handle your files.

What is a MSU file?

A .MSU file is a Windows Update Package file.

Files containing the .msu file extension are update installer files used by the Windows operating system. Files with the .msu extension contain updates for files and applications.

There are four elements in each MSU file, including the update metadata, a CAB file (or multiple CAB files), an XML file, and a properties file. The metadata portion of the MSU file describes the update package. The CAB file (or files) contains the actual update data. The XML file contains the information describing the contents of the MSU file. The properties file is the portion of the MSU file that is read by the Wusa.exe application. The Windows Update utility uses this information to run the update on the user's computer.

Before Vista, Windows would use MSI files for system updates rather than MSU files.

How to open MSU files

Important: Different programs may use files with the MSU file extension for different purposes, so unless you are sure which format your MSU file is, you may need to try a few different programs.

We have not yet verified any programs for Windows that work with this specific file format. If you know one, please use the 'Suggest a program' link below. Thanks!

Last updated: December 4, 2010

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