Windows 11 KB5124010 preview update: Features and bugs

Microsoft has released the optional, non-security preview update KB5124010 for Windows 11, moving version 25H2 to build 26200.9550 and version 24H2 to build 26100.9550. The update, which rolled out on September 22, adds accessibility toggles, keyboard customization, and File Explorer refinements, alongside fixes for existing bugs, but Microsoft has also disclosed two new known issues.

Copilot key remapping and "open apps maximized"

The standout addition is native remapping of the dedicated Copilot key. Users can now set it to act as the right Ctrl or Context Menu via Settings, preserving legacy shortcuts and accessibility workflows.

Microsoft has also added an "open apps maximized" toggle under Settings > Accessibility > Visual effects. When enabled, app windows launch full screen by default, reducing friction for screen reader users, tablet users, and anyone who prefers a consistent full-screen workspace.

File Explorer, Bluetooth, and touchpad fixes

File Explorer now preserves expanded and collapsed section states on the Home page, improves thumbnail reliability for cloud files in the Details pane, and fixes a bug where clicking near the address bar could wipe out typed text.

Precision touchpads gain new single-finger edge scrolling and automatic scrolling gestures. On the Bluetooth side, Microsoft has fixed a 0x139 blue screen crash triggered during Bluetooth audio streaming and resolved a bug where the Bluetooth toggle showed as on even when the radio was off.

Elsewhere, WinRE can now reuse saved Wi-Fi profiles during recovery scenarios like quick machine recovery, and Sysmon gets fixes for process-tampering false positives and a driver crash tied to file monitoring.

Emoji, widgets, and personalization

The update also brings Emoji 17.0, adding new emoji such as distorted face, fight cloud, and hairy creature, plus redesigns of existing ones like saluting face and goose. A new Tips widget offers short feature guidance and can be added to the Widgets board or lock screen. A new Camera roll backup flow in Settings lets users protect photos via OneDrive, set up with a QR code from a mobile phone.

Several desktop background reliability fixes have landed too, including support for DIB wallpaper files, improved slideshow behavior across multiple desktops, and better previews on portrait-mode monitors. The Magnifier taskbar also gets a visual refresh, and the Ebrima font now supports the Garay and Beria Erfe scripts.

Windows Backup and Kiosk Mode

Microsoft has removed the PC-to-PC migration feature entirely; Windows Backup is now the only supported way to move files and settings to a new PC. In kiosk mode, the Windows+Tab shortcut is now disabled in restricted UX kiosks, and Windows+A and Windows+C are disabled in single-app kiosk mode.

Known issues

Microsoft is also warning of two problems tied to this update branch. On Credential Guard–protected, domain-joined devices, some machines may lose their secure trust relationship with Active Directory, blocking interactive sign-in; a registry workaround is available. Separately, some USB Audio Class 1.0 devices may throw a Device Manager Error Code 10 or produce no sound at all. Microsoft says fixes for both are in progress.

Notably, KB5124010 is also the final non-security preview update for Windows 11 24H2, which reaches end of support in October.