KB5079391

Microsoft has released a preview update KB5079391, which turns Windows 11 version 25H2 (2025 Update) into build 26200.8116. This is not a new system, but a small enablement package that activates already existing but previously disabled features.

If you have Windows 11 24H2 installed with the latest updates, to upgrade to 25H2 you only need to install the activation package KB5054156 (eKB) and restart your computer – most changes are already downloaded and waiting for activation, so the installation is as fast as a regular monthly update.

• Narrator (image descriptions). Narrator can now generate detailed descriptions of images. On Copilot+ PCs, descriptions are generated locally on the device; on other Windows 11 devices, they use Copilot integration. Keyboard shortcuts: Narrator + Ctrl + D (describe selected image) and Narrator + Ctrl + S (describe entire screen content). The image is sent to Copilot only after user confirmation. This feature is not available in European Economic Area (EEA) countries.
• Smart App Control. Smart App Control (SAC) can now be enabled or disabled without a clean install of Windows, via Settings > Windows Security > App & browser control > Smart App Control settings. SAC blocks untrusted or potentially malicious apps before they run.
• Updated About system interface. The Settings > System > About page has a more structured look, with improved navigation to related device components, including quick access to storage settings. The device info card on the main Settings page now displays key specifications in a more convenient format.
• Settings performance. Improved loading performance of the main Settings page and reliability of loading required updates in Settings > System > Advanced.
• Microsoft 365 subscription settings. Microsoft 365 Family users can switch to another plan directly from Settings > Accounts. To hide the subscription upgrade offer, you can disable Suggested content.
• Account dialog design. Updated design for dialogs in Settings > Accounts > Other users – the interface matches modern Windows style and supports dark theme.
• Digital pen settings. Added a new option Same as Copilot key, allowing you to assign the pen tail button to launch the same app as the Copilot key.
• File Explorer (voice input and sorting). When renaming files in File Explorer, you can now use voice input (Win + H). In the Advanced Security Settings window for folders, you can now sort permission entries by the Principal column.
• Monitors with refresh rates above 1000 Hz. Monitors can report refresh rates above 1000 Hz to the system if the hardware supports such values.
• Power saving via USB4. When using a native monitor connection over USB4, the USB controller can enter a minimal power consumption mode while the PC is asleep, saving battery charge on laptops.
• HDR and DisplayID improvements. Improved HDR stability on displays with incorrect DisplayID 2.0 blocks; monitors with DisplayID support transmit more accurate screen size information via WMI.
• Printer support change. Updated minimum base system version for printer connectivity – support now extends to Windows 10 version 1607 and Windows Server 2016 (Build 14393).

Known issues and specifics:

Narrator image description feature is not available in European Economic Area (EEA) countries. Availability of Smart App Control depends on device and region. The update rollout is phased: gradual rollout (new features appear on devices gradually, availability may vary) and broad distribution (fixes are released simultaneously for all supported devices).

The update also improves: reliability of unlocking internet files in File Explorer, automatic screen rotation after sleep, HDR performance, Windows Hello fingerprint sign-in, taskbar loading in Safe Mode, number recognition in English voice control, applying Start menu layout via Group Policy, and MIDI message handling.

The PowerShell Set-RDSessionCollectionConfiguration command now recognizes the DisableSeamlessLanguageBar parameter. Removed an unnecessary error message when running sfc /scannow.

In broad distribution: improved Natural Voices performance in Narrator and increased stability of Windows RE when running x64 applications on ARM64 devices.

Installation: cumulative update KB5079391 for PCs is installed manually via Windows Update. Go to Settings > Windows Update and click Check for updates.

When you see 2026-03 Preview Update (KB5079391) (26200.8116), click Download and install. A system restart is required to complete installation. After updating, the Windows 11 build number will change to 26200.8116.

How the new features work:

Narrator (image descriptions): On Copilot+ PCs, generation runs locally via NPU using a small language model (SLM). On other PCs, the request goes to cloud Copilot after explicit user confirmation (commands Narrator+Ctrl+D or +Ctrl+S). Feature unavailable in EEA countries due to regulations.

Smart App Control: SAC uses cloud reputation analysis and code signing. When enabled via Settings > Windows Security > App & browser control, a filesystem filter driver checks PE files before execution. Blocked apps receive status BlockedBySmartAppControl and never load into memory.

Updated About system interface: The Settings > System > About page uses card-based layout with explicit links to storage and memory pages. The main device card pulls data via WMI (Win32_ComputerSystem) and shows CPU, RAM, and OS version compactly.

Settings performance: Main page loads faster due to async tile loading via XAML Islands and deferred COM initialization. Update loading reliability on Settings > System > Advanced improved with exponential backoff retries.

Microsoft 365 subscription settings: Through Settings > Accounts, the Microsoft Entra ID licensing API returns available plans. Plan switching launches a Store websocket session. Disabling Suggested content hides the upsell card at visual tree level.

Account dialog design: User creation dialogs in Settings > Accounts > Other users rewritten in WinUI 3, supporting themes via ThemeResource bindings. Uses Windows.AccountsBroker for secure input without CredUI.

Digital pen settings: Added Same as Copilot key option in HID pen driver. Pressing the tail button sends the same registered ShellExecutable app ID. Remapping uses VirtualKeyCode mapping.

File Explorer (voice input and sorting): Renaming activates an edit field where Win+H inserts speech recognition text from Microsoft Speech Platform. In Advanced Security Settings, sorting by Principal enumerates ACL via GetSecurityDescriptor and compares SIDs without RPC loops.

Monitors with refresh rates above 1000 Hz: EDID extends vertical rate bytes to 16 bits via DisplayID. The dxgkrnl driver accepts up to 65535 Hz in VTotal/RefreshRate DDI fields. USB4 transparently passes DisplayPort packets with >1000 Hz timings.

Power saving via USB4: During sleep (S3/Modern Standby) with native monitor over USB4, the USB4 controller puts some host pipes into D3cold. Enabled by a separate clock lane for the monitor retimer, requiring no host polling.

HDR and DisplayID improvements: Patcher fixed for malformed DisplayID 2.0 blocks (e.g., invalid tF69 brightness set). WMI class WmiMonitorID returns accurate diagonal and pixel pitch. HDR stack ignores corrupted metadata and uses defaults.

Printer support change: Changes in print spooler and PRINTINFO* APIs raise minimum target build to build 14393 (Win10 1607 / Server 2016). Older printer drivers using early EnumPorts calls stop loading without back-compat.

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