Windows 11 KB5063878 is a mandatory update that introduces features such as Quick Machine Recovery, improved stability, and enhanced system performance. The update will automatically download and install, identified as the 2025-08 Cumulative Update for Windows 11 Version 24H2 for x64-based Systems (KB5063878), advancing systems to Windows 11 Build 26100.4946. It addresses stability issues reported after the May 2025 updates, particularly in gaming scenarios. Direct download links for offline installers (.msu) are available on the Microsoft Update Catalog.
The update includes a new Settings UI with an AI-powered search bar, enhancements for handheld gaming, a redesigned Black Screen of Death (BSOD), and Quick Machine Recovery for unbootable systems. Users in Europe with Copilot+ PCs gain new AI features like Recall, which can be disabled through Privacy & Security settings.
Fixes in this update include resolving Windows Firewall errors, issues with the Local Security Authority Subsystem Service (LSASS), visibility problems in File Explorer, and bugs affecting the Settings app and laptop lid options. Microsoft is unaware of any current issues with the update and will continue testing.