KB5074168

Microsoft released cumulative update KB5074168 (Build 28020.1495) for Windows 11, version 26H1. Windows 11 Insider Preview build 28020.1495 is a development branch (br_release) build available to Windows Insider program participants in the Canary channel. Users in this channel now receive updates for Windows 11 version 26H1 (build 28020), which are activated based on Windows 11 version 26H1 (build 28000) using the feature enablement package KB5073122.

• Desktop background image. Recent Canary builds added the ability to use .webp format images as desktop backgrounds via Settings > Personalization > Background. This allows using more compact images without noticeable loss of quality.
• System stability and quality improvements. The update includes a small set of general improvements and fixes aimed at increasing stability and overall system quality for insiders using this build.
• Fix for dialog box cropping. Fixed an issue where the edge of the warning dialog box when shutting down the PC (if other users are active on the system) was cropped by the Start menu border.
• Fix for screen flicker when drawing with a pen. Fixed an issue that could cause brief black screen flickering when using a pen to draw or annotate in the Snipping Tool app.
• Fix for false reboot during shutdown. Fixed an error in recent Canary builds where on some insider devices the system shutdown process appeared as a reboot.
• Fix for Windows Update page freezing. Fixed an issue where the Windows Update page in the Settings app could freeze while loading.
• Fix for loading language components for Australia. Fixed an error where language components in Settings > Time & Language > Language & Region for the Australia region (English – Australia) would not load — the download button did not respond.
• Fix for blue screen error IRQL_NOT_LESS_OR_EQUAL. Fixed an issue where a small number of insiders in recent builds encountered a blue screen (BSOD) with error IRQL_NOT_LESS_OR_EQUAL related to using certain smart card readers.

New issue: a watermark with an incorrect build number is displayed on the desktop. Microsoft is aware of the issue and is working on a fix for future updates.

New issue: an internal error has been discovered that may sometimes cause all open windows and File Explorer tabs to unexpectedly switch to the desktop or to the home page in File Explorer.

Installation via Windows Update: go to Settings > Windows Update and click Check for updates. A computer restart is required to complete the installation.

How the new features work:

Using .webp for desktop background: The system now supports .webp via Settings > Personalization > Background. The image loader checks the extension and WEBP container, then decodes it through WIC (Windows Imaging Component) into a raster format compatible with DWM. This reduces file size while preserving quality.

General system stability improvements: The build includes targeted fixes in the kernel (ntoskrnl.exe), memory manager, and drivers. Rare race conditions and handle leaks that affected long‑session stability are eliminated. Changes primarily affect the Win32k subsystem and the thread scheduler.

Fix for dialog box cropping: Fixed a coordinate calculation error for the shutdown warning dialog. Previously, window boundaries were incorrectly clipped to the Start menu rectangle due to Z‑order mismatch. The system now correctly handles the dialog’s HWND as topmost with priority above StartMenuBorder.

Fix for screen flicker when drawing with a pen: Resolved a conflict in DirectX buffer switching during pen input in the Snipping Tool. The system now properly blocks DPMS (Display Power Management Signaling) changes during an active ink input session, eliminating brief black flicker.

Fix for false reboot during shutdown: Fixed a power‑state transition logic error in ACPI. Previous builds incorrectly set the SHTDN_REASON_FLAG_BOOT flag. The system interpreted a normal shutdown as a failure and activated the boot recovery mechanism, visually appearing as a reboot.

Fix for Windows Update page freezing: Resolved a deadlock in the UsoCoreWorker update scheduler. Loading the Settings page made a synchronous call to the Windows Update service’s COM server, which rarely returned control. Fixed timeout and event handle corruption.

Fix for loading language components for Australia: The registry for the Australia (en-AU) region lacked the correct metadata path for language packs. Fixed an error in the AppxManifest for the resource provider. The download button now calls the proper RegisterLanguagePack function inside LanguageComponentsInstaller, and component assembly starts normally.

Fix for IRQL_NOT_LESS_OR_EQUAL blue screen: The error occurred in the smart card driver WudfUsbccidDriver.dll due to improper IRQL handling on the USB bus. Fixed an improper raise to DISPATCH_LEVEL without lowering it. Access to smart card memory pages now occurs at the correct APC_LEVEL, eliminating the BSOD.

The last 10 Windows updates: