If an updated Windows app, such as Notepad, is installed, does it over-write the existing C:\Program Files\WindowsApps\Microsoft.WindowsNotepad_xxxxxx folder contents?

Windows Store (MSIX/AppX) apps such as Notepad, 3D Viewer, and Paint 3D are installed under C:\Program Files\WindowsApps and are treated as read‑only, versioned packages.

From the provided information:

• Packages under C:\Program Files\WindowsApps are read‑only: writes inside the package are not allowed.
• Each package is uniquely identified by its Package Full Name; it is an error to have two different packages with the same Package Full Name.
• Windows Store apps are all installed to the common C:\Program Files\WindowsApps location.

Implications for the questions:

1. When an app like Notepad is updated
   • The updated app is delivered as a new MSIX/AppX package with a new Package Full Name (typically including a higher version).
   • Because each package is uniquely identified and package contents are read‑only, the update is not an in‑place overwrite of the existing folder contents. Instead, Windows installs the new version as a separate package (separate folder under WindowsApps) and updates the registration so the system uses the new version. Older versions may remain side‑by‑side until Windows cleans them up.
2. Does installing updates create a new subfolder or overwrite the existing one?
   • It effectively creates a new package (new subfolder under C:\Program Files\WindowsApps with a different Package Full Name) rather than overwriting the existing folder contents.
3. If the app is uninstalled from Settings → Apps → Installed apps
   • The package is read‑only and managed by the app deployment system. Uninstall removes the package registration and allows the system to clean up associated files.
   • The documentation emphasizes that app data and package content are tracked so they can be cleaned up on uninstall to reduce system “rot.” This means the WindowsApps package folder for that app/version is not intended to be left behind as an active install. Any remaining artifacts are under system control and not for manual management.

In practice, for vulnerability remediation, updating the app via Windows Update or Microsoft Store installs a new, versioned package under WindowsApps rather than overwriting the existing folder, and uninstalling via Settings removes the app’s registered package so it is no longer present as an installed app.

References:

• Understanding how packaged desktop apps run on Windows
• Security app detection rules update
• An overview of Package Identity in Windows apps