KB5124040


Microsoft has released cumulative update KB5124040 (Build 26220.9223) for Windows 11 version 25H2, intended for insiders on the Beta channel. This build includes improvements in accessibility and Microsoft Store, aimed at enhancing the convenience of working with the system and expanding functionality for developers.

To install update KB5124040 (Build 26220.9223), you need to go to Settings > Windows Update and click Check for updates. A computer restart is required to complete the installation. The update is available only to Windows Insider program participants on the Beta channel.

Feature / Change Performance Increase / Decrease Optimization PC Speed Impact Gaming Optimization
Automatic maximization of application windows (Open apps maximized) ⚪ No measurable change (UI automation only) 🟡 Minor workflow optimization — removes manual step ⚪ Negligible (no background load) ⚪ Not applicable
In-app purchases in packaged WinUI 3 apps requiring elevation ⚪ No direct impact on local performance 🟢 High for developers — built-in commerce platform integration ⚪ Negligible (network/backend only) ⚪ Not applicable

Find and Change Settings

Setting Where to find How to change
Open apps maximized Settings > Accessibility > Visual effects Open Settings > Accessibility > Visual effects. Turn on "Open apps maximized" to automatically maximize application windows when they are opened. Turn it off to keep the default window size behavior.
In-app purchases in packaged WinUI 3 applications (elevated) Microsoft Store (developer/consumer purchase flow) No user-facing setting is required. When a packaged WinUI 3 application that requires elevation offers an in-app purchase, the Microsoft Store commerce platform handles the transaction automatically. Users complete the purchase through the Store purchase dialog. Developers enable this through the Store commerce platform; end users do not change a setting.

Official announcement on the Microsoft website.

The last 10 Windows updates:

Update Build Version Windows Channel Date
KB5121132 28120.2760 26H1 Windows 11 Experimental 2026-08-21
KB5124040 26220.9223 25H2 Windows 11 Beta 2026-08-21
KB5124042 26340.9233 26H2 Windows 11 Experimental 2026-08-21
KB5121106 28020.2731 26H1 Windows 11 Beta 2026-08-17
KB5121109 28120.2738 26H1 Windows 11 Experimental 2026-08-17
KB5124036 26220.9202 25H2 Windows 11 Beta 2026-08-17
KB5124038 26340.9212 26H2 Windows 11 Experimental 2026-08-17
KB5120996 28000.2796 26H1 Windows 11 Preview 2026-08-14
KB5120998 26200.9267 25H2 Windows 11 Preview 2026-08-14
KB5120240 22631.7517 23H2 Windows 11 Stable 2026-08-11