Microsoft pushed the January 2026 Patch Tuesday for Windows 11 today, delivering cumulative update KB5074109 for both 24H2 and 25H2 systems. The update fixes a raft of bugs and rolls out several previously teased features, including a new taskbar shortcut that lets you share any window directly with Copilot.

What’s in the January 2026 cumulative update

After installing KB5074109, Windows 11 25H2 devices land on Build 26200.7623, while 24H2 systems move to Build 26100.7623. The update is mandatory for consumer servicing channels and downloads automatically unless you’ve paused updates. Microsoft has posted standalone .msu packages on the Update Catalog — weighing in at roughly 4.2 GB for x64 and 3.9 GB for ARM64, larger than typical because the company bundles on-device AI model payloads like the Phi Silica family into the offline installers, even for non-AI PCs.

The update addresses several known pain points:

  • Driver removals: Microsoft yanked agrsm64.sys, agrsm.sys, smserl64.sys, and smserial.sys — likely for security, with modern networking alternatives included.
  • WSL + VPN fix: A bug that broke Windows Subsystem for Linux when accessing resources over a VPN, first reported after the November 2025 updates, is now patched.
  • Azure Virtual Desktop errors: Remote Desktop connections in fixed AVD environments no longer stumble.
  • NPU power penalty: Microsoft corrected a processor-performance dip caused by neural processing unit activity on some PCs.
  • SQLite security: WinSqlite3.dll gets a security refresh.
  • Secure Boot certificates: Eligible devices will receive new Secure Boot certs, a change aimed at enterprise environments.

Alongside these fixes, the cumulative acts as a vehicle for staged feature rollouts that first appeared in December 2025. Not every device will see them immediately — they’re gated by Microsoft’s Controlled Feature Rollout (CFR) machinery.

The features rolling out now

Share with Copilot on the taskbar

Hover over an app thumbnail on the taskbar, and a “Share with Copilot” button may appear. Clicking it launches Copilot Vision scoped to that window, letting the assistant analyze what’s on screen — summarize text, translate content, or guide you with an AI cursor overlay that highlights where to click. The feature taps into a Shell API originally meant for communication apps like Teams; Microsoft gave itself a green light, while third-party assistants would need special approval to use the same hook. You must explicitly confirm sharing before Copilot receives a snapshot. If you’d rather not see the option, turn it off under Settings > System > Taskbar > Taskbar behaviour by setting “Share any window from my taskbar” to “None” or “Communication apps.”

A new “Recommended” section in File Explorer Home surfaces files you frequently use and recently downloaded items, distinct from the raw Recent list. It requires a Microsoft account and can be enabled via File Explorer Options. The feed first rolled out to enterprises and is now reaching consumer devices.

Dark mode that actually works consistently

Copy/move/delete confirmation dialogs, progress indicators, and error messages now respect the system dark theme much more reliably. Microsoft previously acknowledged a white-flash regression in early previews, and while not every scenario may be perfect, this update substantially reduces jarring bright dialogs.

Advanced Settings hub

A new Settings > System > Advanced Settings page centralizes toggles for virtualization and sandboxing — Hyper-V, Windows Sandbox, Virtual Machine Platform — moving these out of the legacy Control Panel optional features dialog for better discoverability.

Full Screen Experience for handhelds

Windows’ controller-first “Full Screen Experience” (FSE) posture is now available on all gaming handhelds. When toggled on under Settings > Gaming, the taskbar and desktop elements hide, the Xbox app takes over, and background processes are trimmed to free memory and CPU for games.

Performance refinements

Microsoft widened a fix that reduces stutter when apps query monitor modes at launch, particularly helpful on high-resolution or multi-monitor setups. HID-compliant keyboard backlight performance also gets a lift.

What this means for you

For home users

If your PC is set to receive updates automatically, KB5074109 will install in the background and likely require a restart. The download may feel chunkier than past Patch Tuesdays — expect around 5 minutes on a 200 Mbps connection, with installation taking 7–10 minutes on typical hardware. Once you’re on Build 26200.7623 (or 26100.7623), look for the new features; if you don’t see them right away, they may appear over the coming days as Microsoft flips server-side flags. The update is safe for most users, but keep an eye out for any white flashes in File Explorer if you use dark mode — they should be rare now.

For administrators and IT pros

Treat this as a standard monthly cumulative with important security fixes, but plan for larger offline package sizes (over 4 GB) due to AI model bundling. If you deploy via the Microsoft Update Catalog, note that the combined SSU+LCU .msu files have persistent servicing stack changes — rollbacks can get messy. Pilot the update on representative hardware: test Copilot+ devices if you have them, validate drivers (GPU, NPU, virtualization), and verify that line-of-business apps behave. The Shared with Copilot taskbar option may appear on managed devices; there’s no Group Policy toggle yet, so you’ll need to guide users or use custom configurations if you want to suppress it. For offline deployments, ensure the latest Servicing Stack Update is installed before applying the cumulative, and use DISM /Online /Add-Package /PackagePath: to handle multiple .msu files in sequence.

For developers

The Shell API that powers the “Share with Copilot” button is gated, meaning third-party assistant vendors (like OpenAI for a potential “Share with ChatGPT”) can’t just waltz in and add a similar taskbar integration without Microsoft’s blessing. This could shape competitive dynamics on the Windows taskbar.

How we got here

Microsoft’s 2025–2026 servicing rhythm has been steady: monthly Patch Tuesdays deliver security and reliability fixes while acting as trojan horses for staged feature rollouts. The company leans heavily on CFR, turning on UI and AI features per-device rather than in a big-bang release. December 2025’s cumulative introduced the first wave of Copilot taskbar sharing and dark-mode dialog updates, but many users didn’t see them. January’s pack expands availability significantly.

The ballooning update size is a direct consequence of on-device AI. Starting in 2025, Microsoft began publishing separate component KBs for Phi Silica small language models on Copilot+ PCs. Those model binaries now routinely get packaged into the monthly offline bundles, so even devices that can’t run them locally download gigabytes of AI components. While this simplifies deployment for supported hardware, it frustrates users on metered connections or with limited storage.

Dark mode inconsistencies have been a top user gripe since Windows 11’s launch. Microsoft has chipped away at them across builds — File Explorer, context menus, and now dialogs — but the work is painstaking because legacy Win32 surfaces don’t automatically inherit the modern UI framework’s theming.

What to do now

  • Update automatically: For most home users, let Windows Update do its job. The express/differential delivery will likely be smaller than the offline .msu size.
  • Check your build: After installation, verify via winver or Settings > System > About that you’re on Build 26200.7623 (25H2) or 26100.7623 (24H2).
  • Explore new features: Open File Explorer and see if the Recommended feed appears; hover over taskbar thumbnails to check for “Share with Copilot”; visit the new Advanced Settings page.
  • Turn off unwanted features: If the Copilot taskbar option bugs you, follow the path above to disable it. Similarly, you can switch off the Recommended feed in File Explorer Options.
  • Admins: Download the correct .msu packages for your architecture from the Update Catalog, stage them in a pilot ring for 48–72 hours, and monitor driver compatibility. Back up systems or capture an image before mass deployment. If you use offline servicing, place all .msu files in a single folder and use DISM /Online /Add-Package /PackagePath:C:\Packages\Windows11.0-KB5074109-x64.msu to let the tool sequence prerequisites automatically.

Looking ahead

Microsoft shows no signs of slowing its Copilot integration into Windows shell surfaces. With the taskbar API now available (in a controlled fashion), we may see other assistant vendors negotiate access later this year. Dark mode refinements will continue — further dialog polishing and an eventual fix for the occasional white flash are likely in spring cumulatives. And as on-device AI models evolve, expect monthly update sizes to remain hefty; Microsoft may need to offer modular downloads for users who don’t own Copilot+ hardware. For now, KB5074109 stands as a solid, if heavy, start to 2026’s patching cycle.