UWP App Updates

By default, UWP apps installed from the Microsoft Store update automatically in the background: Windows periodically checks Partner Center's servers for a newer published Version of an installed package, downloads it, and installs it without interrupting the running app, thanks to MSIX's ability to service files that aren't currently locked and finish the swap on next launch or a brief handoff. Users can also trigger a manual check via the Store app's Downloads and updates page. Because every MSIX install/update is atomic and reversible, a failed or interrupted update never leaves the app in a half-updated, broken state — it simply retries or rolls back to the last good version.

Rather than re-downloading an entire package on every update, MSIX supports differential (delta) updates using a block map — a per-file hash manifest (AppxBlockMap.xml) generated automatically when the package is built. When a new version is published, the Store compares block maps between the old and new package and downloads only the changed 64KB blocks, which can shrink a 200MB update to a few megabytes for a small code change. This is especially valuable for apps with large asset payloads like games or media-editing tools, where re-downloading everything on every patch would be wasteful for both Microsoft's CDN and the user's bandwidth.

Apps distributed outside the Store — via sideloading, Intune, or Microsoft Endpoint Configuration Manager — don't get automatic Store polling, so update delivery is the IT administrator's or developer's responsibility. Enterprises typically use an MSIX App Attach or Intune line-of-business app policy that pushes a new package version on a schedule, or the developer can host an AppInstaller file (.appinstaller) referencing the latest package URI, which lets the installed app periodically check that URI itself and prompt or silently self-update, provided the app was originally installed via that same .appinstaller mechanism.