Opening MSU Files

The MSU file type is primarily associated with Wusa.

MSU	File extension: MSU
	File type:	standalone update installer

What is an MSU file?

MSU files mostly belong to Wusa by Microsoft. An MSU file is a standalone system update installer package for Windows operating system. It contains one or more CAB files (one for each update), an XML file describing each CAB file, a properties file, and metadata describing all contents of the MSU package. Windows Update Standalone Installer (Wusa.exe) is a built-in Windows program which installs an MSU package after it is downloaded from the Internet. Another type of MSU file contains data used by Blaise multiplatform questionnaire/interview development and dissemination software.

How do you open MSU files?

You need a suitable software like Wusa to open an MSU file. Without proper software you will receive a Windows message "How do you want to open this file?" or "Windows cannot open this file" or a similar Mac/iPhone/Android alert. If you cannot open your MSU file correctly, try to right-click or long-press the file. Then click "Open with" and choose an application. You can also display a MSU file directly in the browser:. Just drag the file onto this browser window and drop it.

Online MSU Text Viewer

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Online File Viewer

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Programs that open and convert MSU files:

Wusa by Microsoft
See the previous paragraphs to learn more about the main application. MSU files are often referred to as Wusa miscs because this type of file is primarily created or used by this software.
Blaise (data) by Statistics Netherlands
Blaise is a multiplatform computer-assisted survey processing and interviewing software. It uses some data saved in a file with MSU filename extension. This file format is classified as Data.

MSU file extension format:

Each file has a definite file format, that is, how the stored data is arranged in the file. The initial characters of a file are called signature, sometimes also referred to as "magic bytes". The signature can be used to infer the file format. However, different programs can use the same file extension, and file extensions can be assigned incorrectly. If there are problems opening a file, you must first determine the file format used. Our evaluation of the MSU files looks like this:

The file type with the extension 'MSU' mainly uses a defined MSU format. The file formats most commonly found in MSU files are:

97% of all MSU files are Windows Update Package files, which are using the popular CAP file format. CAP files are compressed archives. The first bytes (the signature) are 'MSCF' (short for MicroSoft Cabinet File). These files contain neither text nor words, but only data. A typical file size is 17 MB. The file type is relatively new. The files contain the following words: MSCF, WSUSSCAN.cab, Windows6 and pkgProperties. These files are attributed to windows, refresh, pack, feature, media and andw.

The remaining 3% of all MSU files are different files with different signatures. If you want to find out what your MSU file contains, drag and drop it onto this page.

Technical Data for MSU File Extension

File classification:

Misc

Mime type:

application/vnd.ms-cab-compressed, text/xml

The following listing is compiled from the database produced by the 'Associate This!' program, selected data from the main FILExt database and file extension information submitted by users.

ProgramID: Microsoft.System.Update.1
EXEFile: %systemroot%\system32\wusa.exe %2 %3 %4

ProgramID: Microsoft.System.Update.1
EXEFile: %systemroot%\system32\wusa.exe %2 %3 %4 %5 %6 %7 %8 %9

an msu standalone update installer is a special file format by Microsoft and should only be edited and saved with the appropriate software.

How to solve problems with MSU files

Associate the MSU file extension with the correct application.
Update your software that should actually open standalone update installers. Because only the current version supports the latest MSU file format. Search, therefore, e.g. on the Microsoft manufacturer website after an available Wusa update.
To make sure that your MSU file is not corrupted or virus-infected, get the file again and scan it with Google's virustotal.com.
Click here to open your .MSU file online - secure, fast, and no downloads needed.