wusa.exe: Windows Update Standalone Installer

wusa.exe, also known as the Windows Update Standalone Installer, is a built-in command-line utility in Windows operating systems. It's used to install update packages, typically with .msu (Microsoft Update Standalone Package) extensions. These .msu files contain updates, hotfixes, or service packs for Windows components. wusa.exe extracts the contents of the .msu file and utilizes the Windows Update Agent to apply the changes to the system.

Purpose and Functionality

The primary purpose of wusa.exe is to provide a way to install updates offline or when the regular Windows Update service is unavailable or malfunctioning. It's particularly useful in scenarios like:

• Offline Updates: Installing updates on computers that don't have an internet connection.
• Troubleshooting: Resolving issues where Windows Update is failing to install updates automatically.
• Scripted Deployments: Automating update installations in enterprise environments or custom imaging processes.
• Specific Updates: Installing individual, targeted updates or hotfixes, rather than a full set of cumulative updates.
• Uninstalling Updates: wusa.exe can also be used to uninstall specific updates.

wusa.exe handles the process of checking applicability of updates, integrating the updates into the system, and, if necessary, prompting for a system restart.

Origin

wusa.exe has been a standard part of Windows since Windows Vista and Windows Server 2008. It's a core component of the Windows Update infrastructure and is provided by Microsoft as part of the operating system. It's located in the %windir%\System32 directory (usually C:\Windows\System32).

Usage

wusa.exe is a command-line utility. You need to use it from either Command Prompt (cmd.exe) or PowerShell, preferably running as an administrator. Here's a breakdown of its syntax and common usage scenarios:

Basic Syntax: