Microsoft Windows 11 26H2 Update Version OS Build 26300.9550

KB5124010 updates Windows 11 version 26H2 to OS Build 26300.9550 with new File Explorer, emoji, accessibility, touchpad, Copilot key, camera backup, and WinRE capabilities, plus quality fixes.

• Sysmon now handles malformed executable headers more reliably, preventing unpredictable memory use and improving tampering detection.
• Sysmon no longer incorrectly reports Event ID 25 process-tampering alerts for Windows Session Manager (smss.exe).

• Fixes built-in camera failures in the Camera app and other camera-enabled applications.
• Fixes File History failures when backing up or restoring files to external drives or network locations.
• Improves Bluetooth connection-state reporting, audio stability, microphone compatibility, and Settings reliability.
• Fixes a Sysmon file-system filter driver stop error caused by closing an uninitialized handle.
• Improves Settings reliability for printers and scanners, installed-app version display, time-picker formatting, and camera-sharing preferences.
• Improves laptop power-state detection when a plugged-in device incorrectly switches from AC power to battery power.

• File Explorer can preview downloaded HTML files after confirmation, automatically preview non-HTML files such as PDFs, preserve Home section states, and provide more reliable cloud-file thumbnails.
• Adds Emoji 17.0 support and refines several existing emoji designs.
• Adds the Tips widget for the Widgets board and lock screen.
• Adds the Open apps maximized accessibility setting and improves keyboard, gamepad, and Narrator navigation for Bluetooth quick settings.
• Modernizes the Magnifier taskbar with refreshed icons and spacing while preserving existing controls and shortcuts.
• Adds precision-touchpad single-finger edge scrolling and automatic scrolling gestures.
• Allows the Copilot key to be remapped to Right Ctrl or Context Menu.
• Adds Camera roll backup in Settings for eligible users with OneDrive.
• Adds Garay and Beria Erfe script support and updated Adlam glyphs in the Ebrima font.
• Adds a recovery remote management plug-in for WinRE management by MDM providers.

• Some applications that use AC-3 (Dolby Digital) decoding may fail to launch or close unexpectedly when certain audio features are used.
• Some USB Audio Class 1.0 devices may fail with Device Manager Code 10, produce no audio, or have unavailable or unresponsive sound controls.

• The update is delivered through gradual and normal rollout phases, so availability may vary by device.
• The update includes Servicing Stack Update KB5124009, Build 26100.9539.
• AI components are updated to version 1.2608.951.0, including Image Search, Content Extraction, Semantic Analysis, and Settings Model.
• PC-to-PC Migration is no longer available; use Windows Backup to transfer supported files and settings.
• In restricted UX kiosk mode, Windows+Tab is disabled. In single-app kiosk mode, Windows+A and Windows+C are disabled.
• Feature availability depends on the device and market.

Product Information

Vendor: Microsoft

Product: Windows 11

Product type: Software

Application category: Utilities

Platform: Windows

Variant: 26H2

Version: OS Build 26300.9550

Vendor information published: Sep 22, 2026

Original release notes: View on vendor site

Published on updatealert.io: Oct 5, 2026

Description: Client operating system for modern desktop and enterprise environments.