KB5077239

Microsoft has released preview update KB5077239 (build 28000.1643) for Windows 11 version 26H1. Windows 11 version 26H1 received preview update KB5077239 for PCs with ARM64 architecture processors (Snapdragon). Additionally, the update is available for devices with x64 architecture processors (x86-64, Intel and AMD) that have been updated to version 26H1.

• AI Agent in Windows Settings. The agent in the Settings app now supports more languages — support has been expanded for German, Portuguese, Spanish, Korean, Japanese, Hindi, Italian, and Chinese (Simplified). The search results menu now shows more available results, making it easier to quickly find and change settings. A scrollbar has been added to view the full list of results. Recommended settings now apply changes faster — for recently changed parameters, an integrated agent option appears directly in the interface. A dialog box appears if a setting cannot be changed further: it explains the reason and offers an option to adjust parameters if necessary.
• Click to Do. The Click to Do context menu has received a lighter and more intuitive design. It is now easier to access frequently used actions such as copy, save, send and open, and also to find the desired command faster. If a large image or table appears on the screen, the context menu may open automatically, allowing you to perform actions and see the result immediately.
• Camera. Windows Studio Effects can now also be used for an additional camera — for example, a USB webcam or a built-in rear laptop camera. To enable the feature: go to Settings > Bluetooth & devices > Cameras, select the desired camera from the list of connected devices, open Additional camera settings, and turn on Use Windows Studio Effects. After activation, Studio Effects can be configured on the camera settings page or through the quick menu on the taskbar.
• File Explorer. The placeholder text in the File Explorer search box has been updated to highlight the advanced capabilities of Windows Search. Actions in the Home section on hover (for faster file management) are now available to commercial customers.
• Advanced Settings. An option to enable virtual working environments has been added to Advanced Settings. Virtual working environments allow you to enable or disable virtual environments such as Hyper-V and Windows Sandbox. The section is located at: Settings > System > Advanced.
• Continue on another device. Cross-platform resume capabilities have been expanded. You can now continue actions from an Android smartphone on your PC — for example, continue playing Spotify, work in Word, Excel or PowerPoint, and resume a browser session. Users of Vivo Android smartphones can continue viewing websites from the Vivo browser on their PC. If you use an HONOR, OPPO, Samsung, vivo or Xiaomi Android smartphone, you can resume working with online files opened in the Microsoft Copilot app on your phone. On the PC, files open in the corresponding Microsoft 365 app (if installed), otherwise in the default browser. The feature does not support offline files stored only on the phone.
• Windows MIDI Services. MIDI performance in Windows has been improved — expanded support for MIDI 1.0 and MIDI 2.0, including full WinMM and WinRT support for MIDI 1.0 with built-in translation, shared MIDI ports between apps, configurable port names, feedback and MIDI sharing between apps, as well as performance improvements and bug fixes for a smoother musician experience. The App SDK and Tools package is distributed separately. It includes built-in MIDI 2.0 capabilities and tools such as MIDI Console and the MIDI Settings app. Current versions are available on the Windows MIDI Services and GitHub pages and are currently unsigned, which may cause security warnings when downloading or installing.
• Narrator. Narrator now gives you more control over how interface elements are announced. You can choose which details to speak and customize their order to match your navigation style. These settings apply across the app, helping to reduce unnecessary announcements and make speech prompts clearer.
• Voice Access. The initial setup process for voice access has been updated and simplified. The new flow helps you download the appropriate language model, select your preferred microphone, and understand what tasks voice access can perform on your PC.
• Voice Typing. An Action wait timeout parameter has been added — it allows you to adjust the delay before executing a voice command. This helps recognize commands more accurately at different speech tempos, both slow and fast.
• Windows Hello. Windows Hello Enhanced Sign-in Security (ESS) now supports external (peripheral) fingerprint scanners. Previously ESS was only available on PCs with built-in biometric sensors, and now the more secure sign-in option is also available for desktop PCs and other Windows 11 devices, including Copilot+ PCs. To configure, connect a supported ESS reader, go to Settings > Accounts > Sign-in options and register your fingerprint.
• Windows Update. The process of joining the Windows Insider Program has been improved, and situations where the process could hang when connecting via Settings > Windows Update have been fixed.
• Lock screen. Internal changes have been made to fix cases where the lock screen could become unresponsive.
• File Explorer (interface improvements). More consistent dark mode in File Explorer: copy, move and delete dialogs (in both normal and expanded views), progress indicators and chart views have been updated to better match the dark theme and improve readability. Confirmation dialogs (skip, replace, file selection) and several error windows have also been updated for a consistent look. Simplified File Explorer context menu for easier navigation. Frequent actions (e.g., Send, Copy and Move) are grouped in one structured menu. This reduces clutter and makes it easier to find commands when using a mouse, keyboard or accessibility features. Initially this change is available to a limited set of devices while Microsoft evaluates the optimal approach. The Recommended section on the File Explorer home page simplifies access to frequently used and recently downloaded files. To enable this section, you need to activate the Show Recommended section setting in folder options. The feature is available to all users, including those signed in with a personal Microsoft account.
• File Explorer (fixes and improvements). Internal changes have been made to improve File Explorer responsiveness when navigating to network locations. Improved behavior where File Explorer could unexpectedly fail to show thumbnails for video files containing certain EXIF metadata. More stable File Explorer behavior — the toolbar should no longer appear unexpectedly. Fixed: when right-clicking a file, the app icon next to the Open item could display as a standard icon instead of the icon corresponding to the default app for that file type.
• Sign-in. Improved reliability of the scenario where Explorer.exe could hang during first sign-in, which occurred if some apps were configured to start automatically. This could cause the taskbar not to appear.
• Activation. Improved Windows license migration during update. In some cases, a valid license might not carry over because the device did not register the digital license in time — then the activation troubleshooter was required to complete the process.
• Desktop icons. Improved reliability when opening or renaming files on the desktop — icons should stay in place and no longer move unexpectedly.
• Input. Improved display of labels for key repeat delay settings in Settings > Bluetooth & devices > Keyboard.
• User Account Control (UAC). Improved reliability of launching Windows Terminal with elevated privileges from a non-administrator account — the PC should no longer become unresponsive to requests.
• Windows Sandbox. Fixed an issue where Windows Sandbox could hang on startup and show error 0x800705b4.
• Spotlight on desktop. If you use the Spotlight feature as your desktop background (Settings > Personalization > Background), the context menu now includes two items: Learn more about this image and Next desktop background.
• Games. Xbox Full screen experience (FSE) is now available on more Windows 11 handheld devices following its initial launch on ASUS ROG Ally and ROG Ally X. FSE provides a console-like interface with the Xbox app, reduces distractions and improves performance by minimizing background tasks. Enable it via Settings > Games > Full screen mode, where you need to select Xbox as the home app. You can launch it through task view or the game bar, and also configure it to start in full screen mode when the device starts.
• Pen. Pen devices that support haptic feedback can now provide haptic feedback when interacting with the Windows interface — for example, when hovering over the close button, snapping windows or resizing them.
• Keyboard. Improved keyboard backlight performance on supported HID-compliant keyboards. The backlight helps you see keys better in low-light conditions and can adapt to save power. Enabled the AltGr level for the Arabic 101 keyboard layout. The left Alt key works as before, and the right Alt key becomes a modifier for additional symbols. The first new symbol is the Saudi Riyal currency symbol (AltGr+S). It is also available on the currency tab in the on-screen keyboard and in the symbol picker. Switching languages with Alt+Shift is still available via left Alt+Shift or the Windows+Spacebar combination. The Arabic 102 and Arabic 102 AZERTY layouts have been similarly updated.
• Mobile devices settings. A page for adding and managing mobile devices has been added to Settings > Bluetooth & devices > Mobile devices. Here you can manage features such as using your phone as a connected camera or accessing your phone's files through File Explorer.
• OneDrive. A new OneDrive icon is displayed in Settings > Accounts > Home.
• Settings (migration from Control Panel). The key repeat delay and rate settings and the cursor blink rate have been migrated from Control Panel to the Settings app. Key repeat delay and rate are now in Settings > Accessibility > Keyboard, and cursor blink rate is in Settings > Accessibility > Text cursor.
• Settings (About system section). The About system section in Settings has received an updated layout that combines device information and related settings in one place. For example, you can now quickly navigate to storage settings.
• Settings (reliability and interface). Improved reliability when navigating to Settings > Network & Internet — the Settings app should no longer become unresponsive. The search bar in Settings should no longer overlap the Minimize and Maximize buttons in the window title bar.
• Taskbar and system tray. You can now directly share an open app window with Copilot from the taskbar. When hovering over a running app icon, a Share with Copilot option appears — similar to the window sharing feature in Microsoft Teams. Copilot Vision analyzes the window content and provides suggestions based on what is displayed in the app. The Automatically hide the taskbar setting now works more reliably and no longer turns off unexpectedly after the "Toolbar is already hidden on this side of the screen" message. Voice access now responds more reliably when interacting with the taskbar, including selecting items by number. Improved behavior of taskbar icons — when there is free space, icons maintain the expected size.
• Windows Sharing. The drag bar now supports sending multiple files, shows more relevant apps, and simplifies moving files to a selected folder. The drag bar can now be turned on or off in Settings > System > Nearby sharing. The ability to share OneDrive files through other apps has been introduced. Options appear in the Share with list after selecting Copy link. Sign-in with a Microsoft account is required.
• Display and graphics. Improved performance in scenarios where apps request the full list of supported modes from monitors. Previously this could cause brief hangs on very high resolution monitors — changes aim to reduce and prevent such stutters. Improved behavior of the brightness slider on all-in-one PCs — the system better maintains the selected level and helps avoid unexpected brightness changes. Fixed: the Unsupported video card detected message could appear in some games, even when using a supported video card.
• Game Pass. Mentions of Game Pass in Settings have been updated to reflect current branding and benefit descriptions.
• Start menu. For users with the new Start menu, the Windows search bar now matches its size, providing a smoother transition to search.
• Lock screen and sign-in (fixes). Fixed an issue where first sign-in to a new account could be very slow. Fixed a memory leak that could occur when using slideshow mode on the lock screen. Memory leaks over time can lead to performance and reliability issues.
• Smart cards. Fixed an issue where STATUS_NOT_SUPPORTED (0xc00000bb) could unexpectedly appear when signing in using ECC smart card sign-in credentials.

Cumulative update 5077239 for PCs is installed manually via Windows Update. To check for updates, go to Settings > Windows Update and click Check for updates. When you see that the February 2026 Preview Update (KB5077239) (28000.1641) is available, click Download and install. A computer restart is required to complete installation. After the update, the Windows 11 version 26H1 build number will change to 28000.1641.

How the new features work:

AI Agent in Windows Settings: The agent uses local LLMs and search APIs over policy XML templates and ms-settings: URIs. Language expansion loads new BERT tokenization models. Recommendations apply faster by caching recent registry changes (HKCU...\Settings).

Click to Do: Uses global hooks (SetWindowsHookEx) to intercept mouse events. Content type detection via DirectComposition. Auto‑opening for large images triggers via UI Automation threshold (>800x600). Rendered in a WS_POPUP layer with hardware acceleration.

Camera: Windows Studio Effects apply MFT filters in the camera driver. Enabling for an extra camera adds it to the capture graph (IMFSourceReader) and applies effects via NPU or DirectX compute shader. Registry key binds the effect to a specific DevicePath.

File Explorer: Updated placeholder string in shell32.dll.mui. On‑hover actions in Home use WM_MOUSEHOVER triggers in DirectUIHWND, showing context buttons via DWM transparency animation without full repaint.

Advanced Settings: Enables features via WindowsOptionalFeature.exe with /online /enable /featurename:.... Checks SLAT and available memory. Hyper‑V switches bootloader to hvloader.efi; Sandbox starts a lightweight kernel‑isolated environment.

Continue on another device: Uses nearby.sharing (Project Rome) over Bluetooth LE or Wi‑Fi Direct. App state serialized via Graph API, synced with Microsoft Account. Android sends URI activities; PC calls ms-desktoptoast: to open the file link in MS 365.

Windows MIDI Services: New multi‑user service (midisrv.dll) replaces classic winmm.dll. Uses WinRT MIDI API with 1.0/2.0 protocol translation (7‑bit to 32‑bit). Ports shared via ALPC. App SDK includes MidiConsole.exe and UMDF 2.0 driver. Unsigned driver triggers security warnings.

Narrator: Announcement order uses UIA_PropertyChangedEventArgs filters. The engine (ISpeechVoice) traverses the UI tree but skips nodes with OffScreen or specific roles. Settings saved in registry; narrator.exe applies them via UIA_SelectionItemPattern on focus.

Voice Access: Setup checks for acoustic models (e.g. ms-speech-acoustic-en-us), downloads via Cognitive Services Speech SDK. Master calls MMDeviceEnumerator to select microphone by IMMEndpoint. Background service VAHost.exe loads grammar XML (SRGS) and listens via SetWinEventHook.

Voice Typing: The Action wait timeout parameter controls pause duration after phrase recognition before executing a command. Implemented in the semantic parser layer (dll_recognizer) as end_silence_timeout_ms. Values range 300‑800 ms to prevent false triggers or missed commands.

Windows Hello: ESS for external scanners requires TPM 2.0 and a driver supporting KSP_KEY_TRUSTED_PIN. Biometrics never leave the scanner – only signed hash via WinBio API. Enabling adds the provider to Credential Manager (NGC registry branch).

Windows Update: Insider Program hang fix – added timeout in COM call to wuauserv. Previous deadlock due to pending.xml lock. Now asynchronous queue with retries via BITS, rollback on failure.

Lock screen: Fixed LogonUI.exe freezing because TimeBroker stalled on notifications. Improved WM_WTSSESSION_CHANGE handling and added SetThreadExecutionState(ES_SYSTEM_REQUIRED). Wallpaper cache cleanup on wake.

File Explorer (interface improvements): Dark dialogs use explicit GetSysColor(COLOR_WINDOWFRAME) check and replace standard Win32 dialogs with XAML Islands bound to Application.Current.RequestedTheme. Progress bars use Microsoft.UI.Xaml.Controls.ProgressBar with Composition API color animation.

File Explorer (fixes and improvements): Network location hang – replaced synchronous WNetUseConnection with async via CoWaitForMultipleHandles. Video thumbnail EXIF bug – added orientation tag check in PhotoMetadataHandler. Fixed app icon next to Open item in context menu.

Sign-in: explorer.exe hang during first sign‑in due to race condition in Run registry key. Added 5‑second timeout via RegisterApplicationRestart. Explorer ignores hung processes, forcibly closing handles. Taskbar initialises after queue verification.

Activation: License migration uses LicenseManager::GetDigitalLicenseEx with retries to activation server via SoftwareLicensingService. Added wait state checking IsLicensePersisted flag and calls SLpActivateInternet before POST_OOBE stage.

Desktop icons: Rename fix – previous async IFileOperation::RenameItem reset coordinates due to SysListView32 recreation. Now uses WM_SETREDRAW lock and saves positions via Get/SetPosition in LVITEM.lParam. Icons stay in place.

Input: Fixed labels for Keyboard Delay and Keyboard Speed in Settings. Previously strings from input.dll.mui referenced wrong resource IDs (IDS_REPEAT_DELAY vs IDS_REPEAT_RATE). Now correctly bound via x:Bind and tooltips fixed in XAML.

User Account Control (UAC): Launching Terminal as admin from non‑admin account uses ShellExecuteEx with runas flag. Previous UAC dialog deadlock fixed by ChangeWindowMessageFilterEx for WM_COPYDATA and consent.exe timeout. System no longer freezes.

Windows Sandbox: Error 0x800705b4 fixed – added check for vmcompute service state in wsb.ps1 and forced virtual switch reset via Disable-VmAdapter. Sandbox now waits for wmic.exe response max 10 seconds, then retries.

Spotlight on desktop: Two context menu items added. DesktopBackgroundHandler calls ISpotlightBroker::GetImageMetadata. "Learn more" opens Bing search by image hash. "Next background" forces rotation via EDB.db (Jet Blue), bypassing the 24‑hour timer.

Games: Full Screen Experience for Xbox on handhelds uses IDXGISwapChain::SetFullscreenState and priority tasks PROCESS_MODE_BACKGROUND_BEGIN. Console interface based on XboxGameBarWidget. Activation writes HKCU\Software\Microsoft\GameBar and intercepts guide button.

Pen: Tactile feedback via HID driver with HID_USAGE_TACTILE_EFFECT reports. On hover over a button, system calls SendHapticFeedback with amplitude/duration. DWM tracks hit‑test and passes coordinates via ITabletManager. Requires Microsoft Pen Protocol v3.

Keyboard: Backlight control uses HID_KB_BACKLIGHT with IOCTL_HID_SET_FEATURE. AltGr level for Arabic layout translates VK_RMENU to VK_LCONTROL + VK_MENU. Riyal symbol (U+FDFC) bound to AltGr+S via KBDARB.DLL. Alt+Shift remains at GetKeyState level.

Mobile devices settings: New page calls Windows.Devices.Enumeration.DeviceInformation. Phone as camera uses MTP/PTP; file access via WebDAV or USB. Functions stored in HKLM\Software\Microsoft\Windows\MobileDevices. "Add device" opens Bluetooth wizard or QR linking.

OneDrive: New icon is an interactive WinRT XAML control bound to sync status via CloudSyncStatusManager. Click triggers shell:onedrive. Icon colour changes (blue/grey/gold) using FontIcon with glyphs from Segoe MDL2 Assets. Storage size via Graph API.

Settings (migration from Control Panel): Keyboard repeat delay/rate and cursor blink rate now write directly to HKCU\Control Panel\Desktop (KeyboardDelay, KeyboardSpeed, CursorBlinkRate) and apply via SystemParametersInfo with SPIF_UPDATEINIFILE and SPIF_SENDCHANGE. Old Control Panel no longer intercepts.

Settings (About system section): New layout uses StackPanel with SettingsExpander cards. System info via GetSystemInfo and WMI Win32_ComputerSystem. Quick action buttons navigate via Frame.Navigate without full reload. Adaptive layout.

Settings (reliability and interface): Fixed hang in Network & Internet – replaced synchronous INetworkListManager::GetNetworkConnections with async/await. Search bar overlap fixed via WindowChrome and correct GetSystemMetrics(SM_CXPADDEDBORDER) in OnWindowSizeChanged.

Taskbar and system tray: "Share with Copilot" hover calls IVirtualDesktopManager and GetWindowThreadProcessId. Copilot Vision takes screenshot (PrintWindow) and analyses via local CNN. Auto‑hide fixed by resetting ABE_AUTOHIDE flag on "Toolbar already hidden" error.

Windows Sharing: Drag bar for multiple files uses CF_HDROP clipboard format. Enable activates NearbySharing via WiFiDirectAdvertisementPublisher. OneDrive creates temporary ms-onedrive: link. Microsoft Account required for permission check.

Display and graphics: EnumDisplaySettingsEx now cached in driver, returns only unique resolutions without re‑polling DDC/CI. Brightness slider for AIO fixed via binding to GetMonitorBrightness of ACPI driver, avoiding Intel DPST conflicts.

Game Pass: Strings in SettingsResources.resw updated to reflect current branding (Ultimate, PC Game Pass). Click opens deep URI xbox:subscription?skuId=.... Subscription status via background Xbox Live API call, cached in app isolated storage.

Start menu: Search box width synchronised via VisualStateManager and common SearchBoxWidth property. Uses RelativePanel bound to actual StartMenuHost width, preventing animation breaks.

Lock screen and sign-in (fixes): Slow first sign‑in fixed with LoadUserProfile at HIGH_PRIORITY. Slideshow memory leak – DWM now calls IWICBitmapSource_Release on image change. Prevents worker pool overflow after hours.

Smart cards: Fixed STATUS_NOT_SUPPORTED (0xc00000bb) for ECC cards by checking ALG_ID (e.g. CALG_ECDH_P384) in CardAcquireContext. Falls back to RSA emulation if card lacks direct ECC support, keeping minidriver compatibility.

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