Microsoft Windows 11 26H1 Update Version OS Build 28000.1643

KB5077239 (OS Build 28000.1643) is a non-security preview update for Windows 11 version 26H1. It adds Secure Boot PowerShell tools, expands Copilot+ and Windows features, and includes quality improvements plus the servicing stack update KB5078262.

• Adds Secure Boot management support with Get-SecureBootUEFI -Decoded and Get-SecureBootSVN to help verify Secure Boot keys, certificates, and policy compliance.
• Includes the latest security fixes and improvements from prior updates.

• Improves File Explorer responsiveness, dark mode consistency, context menu behavior, thumbnail display, and network navigation performance.
• Fixes Windows Sandbox startup hangs with error 0x800705b4.
• Improves reliability for sign-in, taskbar behavior, Settings responsiveness, desktop icon stability, UAC elevation from non-admin accounts, and Windows license migration.
• Fixes issues with unsupported graphics card detection in some games and slow first sign-in for new accounts.
• Improves BitLocker recovery experiences and helps prevent hangs after entering the recovery key.

• Expands Settings Agent language support and improves search, recommendations, and adjustment dialogs.
• Adds new Copilot+ PC experiences for Click to Do, camera Studio Effects on more cameras, Narrator controls, Voice Access setup, and Voice Typing delay settings.
• Adds Virtual Workspaces controls in Advanced Settings for Hyper-V and Windows Sandbox.
• Expands Cross-Device Resume for Android phones and supported apps/services.
• Improves Windows MIDI Services with broader MIDI 1.0 and MIDI 2.0 support.
• Adds Windows Hello Enhanced Sign-in Security support for peripheral fingerprint sensors.
• Adds new File Explorer, Desktop Spotlight, Gaming full screen experience, Mobile Device Settings, OneDrive, Windows Share, and taskbar sharing features.

• Release date: 2026-02-24.
• Windows 11 servicing stack update KB5078262 is included and updates the servicing stack to OS Build 28000.1638.
• The App SDK and Tools package for Windows MIDI Services is a separate unsigned download and may trigger security warnings.
• Some features roll out gradually and may vary by device, market, or availability; drag tray is not available in the European Economic Area.
• If earlier updates are installed, only the new updates in this package are downloaded and installed.

Product Information

Vendor: Microsoft

Product: Windows 11

Product type: Software

Application category: Utilities

Platform: Windows

Variant: 26H1

Version: OS Build 28000.1643

Vendor information published: Feb 24, 2026

Original release notes: View on vendor site

Published on updatealert.io: Jun 3, 2026

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