File Extension MSU

File type: Microsoft Update Standalone Package

About the MSU file type:

If Windows cannot find the appropriate program associated with .MSU files, then your registry may have errors. Check your Windows registry for errors (includes file association errors).

The .MSU file extension identifies Microsoft Update Standalone Packages (also known as Windows Vista hot fix Updates). These are usually compressed files which deliver updates or patches for Windows Vista. To extract these files you will need to use the windows Vista Expand utility.

Additional Information:
This extension replaces the .MSI which was used with previous versions of Windows.