Windows 11 KB5065426 (Build 26100.6584): AI models, UI polish, and rollout guidance

Windows 11’s September Patch Tuesday brings a sizeable, feature-packed cumulative update—KB5065426 (Build 26100.6584)—that mixes small but welcome taskbar and File Explorer polish with deeper on-device AI components and an unusually large offline payload that deserves careful attention from both home users and IT teams. (windowslatest.com)

Background / Overview​

Microsoft released KB5065426 as part of the September 9, 2025 Patch Tuesday cycle. The update advances Windows 11 24H2 machines to Build 26100.6584 and is being offered through Windows Update and the Microsoft Update Catalog as an .msu offline installer for administrators and users who prefer manual deployment. Microsoft’s combined servicing approach for Windows 11 (checkpoint cumulative updates) means the cataloged packages may include both SSU and LCU payloads; installing via the Update Catalog remains the recommended manual path. (windowslatest.com) (learn.microsoft.com)
Two facts stand out immediately:

• The update surfaced visible UI changes (taskbar/calendar, permission prompts) and small app-UX improvements (Click to Do tutorial, File Explorer tweaks).
• The offline .msu packages are very large—multiple gigabytes—because Microsoft’s on-device generative AI models for Copilot features are included in the payloads shipped to all architectures. That decision has meaningful implications for bandwidth, disk space, and deployment workflows. (windowslatest.com)

This article unpacks the update, verifies core technical points, analyses the benefits and risks, and offers practical guidance for users and IT administrators planning deployment.

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What KB5065426 delivers: feature roundup​

Headline items​

• Taskbar / Calendar flyout: A full clock view returns to the calendar flyout (similar in function to Windows 10’s full clock), bringing back a larger time display when you open the date/time calendar. This restores a long-requested convenience for users who relied on the expanded flyout clock. (windowslatest.com)
• Recall (Copilot+ devices): The Recall experience gains a new homepage that aggregates recent snapshots, top apps, and recent websites—aimed at faster task resumption on NPU-equipped Copilot+ PCs. Recall remains opt-in and tied to hardware with on-device NPUs. (windowslatest.com)
• Click to Do tutorial: Click to Do now includes an interactive, re-launchable tutorial to improve discoverability of text-and-image assistant actions. (windowslatest.com)
• System permission prompts: Microsoft changed how some hardware permission prompts are presented—displaying a dimmed, focused full-screen prompt in certain scenarios to make consent dialogs more prominent. (windowslatest.com)
• File Explorer UI and AI actions: Explorer receives visual polish and context-menu AI actions (image edits and searches) that surface common workflows inline. These actions are being staged and gated by hardware and licensing (Copilot/Microsoft 365 entitlements in some cases). (windowscentral.com)

Download sizes and payload composition​

Direct .msu download entries posted in the Microsoft Update Catalog report very large downloads:

• ARM64: approximately 3,685.4 MB
• x64 (client): approximately 3,811.1 MB
• x64 (Server 24H2): approximately 3,811.1 MB

Those sizes are strikingly large for a single monthly cumulative update and are comparable to small Windows ISO images. Microsoft has shipped on-device AI model binaries in these packages—models that are technically required to power Copilot capabilities on eligible hardware—even though those models are included in the installers for all systems. This is the primary reason for the multi-gigabyte package sizes. (windowslatest.com) (windowscentral.com)

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Deep dive: key features and technical verification​

1) Recall — new homepage, NPU dependency, and disable options​

Recall’s redesign surfaces a “Home” overview of recent activities and snapshot collections for faster resumption. Multiple reports confirm that Recall depends on specialized hardware—machines designated by Microsoft as Copilot+ with an on-device NPU—and that Recall functionality is opt‑in by design. The update places the UI scaffolding in Build 26100.6584, but server-side gating and hardware checks control full activation. (windowslatest.com, windowscentral.com)
Disabling Recall: WindowsLatest’s coverage shows a DISM command example to disable Recall, but the article’s listing of the DISM command is truncated and needs verification before execution on production PCs. Community guidance and Microsoft documentation recommend first checking the feature state with DISM (for example, DISM /Online /Get-FeatureInfo /FeatureName:Recall) and then using DISM /Online /Disable-Feature with the precise feature name if you want to remove it. Users should verify the exact feature name and syntax in the Windows documentation or by using the DISM feature list on their machine to avoid accidental changes. Treat the quoted command in informal coverage as indicative, not authoritative. (windowslatest.com, answers.microsoft.com)

2) Click to Do — tutorial and improved discoverability​

The Click to Do tutorial is a straightforward UX improvement. It is intended to help users who have turned off first-run guidance re-discover interactive assistant flows. The UI path reported (app > More options > Start tutorial) has been validated by hands-on reporting in preview builds and is consistent with Microsoft’s iterative onboarding approach for AI surfaces. (windowslatest.com, windowscentral.com)

3) System permission prompts — focus + dimming​

Windows now shows a more prominent permission prompt in some cases (full-screen and dimming the rest of the display) to reduce accidental clicks and highlight privacy decisions. This approach follows a general industry pattern—make sensitive permission dialogs obvious and harder to miss. The change is small but meaningful from a usability and privacy standpoint. (windowslatest.com)

4) Taskbar calendar and Notification Center clock​

The return of a fuller clock in the calendar flyout addresses a long-standing user request. The larger flyout clock—optionally showing seconds in some flights—was previously trialed in Insider builds and now appears in servicing updates for broader rings. This move restores a convenience many power users missed after the transition to Windows 11. Experimental Canary/Dev rollouts and staggered server-side gating explain why not every device sees the same exact UI at the same time. (windowslatest.com)

5) File Explorer — visual cleanups and AI actions​

File Explorer’s context menus and right-click AI actions are now intended to act as quick shortcuts to existing editing and search flows (e.g., Bing Visual Search, background removal in Paint/Photos). These items are visible in preview and can be tied to Copilot entitlements or hardware gating. The intent is to surface common image edit and lookup workflows without forcing a full app switch. Expect progressive rollout behavior; not all users on Build 26100.6584 will immediately see every AI action. (windowscentral.com)

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Why the installer is so large — the AI model factor​

The standout operational characteristic of KB5065426 is its size. The offline .msu installers top out near 3.7–3.8 GB per architecture. The root cause is the inclusion of on-device AI models in the cumulative payload that enable offline or low-latency Copilot experiences on qualifying machines (Copilot+). Those models are shipped in the overall package and therefore increase the download and disk footprint for every user, even if their hardware does not qualify to run those models.
This approach simplifies the servicing pipeline (ship once, gate features server-side), but it has trade-offs:

• Increased bandwidth costs for home users and organizations.
• Larger storage needs on images and deployment shares.
• Slower manual installs and longer update windows for machines with limited I/O or storage headroom.

Multiple tech outlets and the Update Catalog listings corroborate the sizes and the model inclusion explanation. Administrators must plan for longer network transfer windows and verify that their imaging/WSUS processes accommodate the extra payloads. (windowslatest.com, windowscentral.com)

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Stability and the SSD corruption reports — what the evidence says​

A spate of user reports in August 2025 linked an earlier Windows 11 August patch (and related servicing updates) to SSD disappearance or corruption on certain systems. Investigations subsequently pointed toward SSD controller firmware—particularly pre-release or engineering firmware from certain vendors (notably Phison)—as the likely root cause for many affected drives. Independent hardware vendor engineering checks and third-party coverage indicate that production firmware versions were not implicated at the same rate. Microsoft also stated that their internal investigations have found no direct connection between the August security update and hard drive failures. Still, the incident highlights the complexity of modern storage stacks and the importance of firmware hygiene. (windowslatest.com, tomshardware.com, bleepingcomputer.com)
Practical guidance:

• Verify SSD firmware is on a released production version; avoid pre-release engineering firmware unless directed by vendor documentation.
• Keep backups before installing major cumulative updates.
• If you suspect storage problems after patching, collect logs and contact vendor support—do not continue heavy writes that could exacerbate a failing SSD.

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Enterprise considerations: deployment and manageability​

• Checkpoint cumulative updates: The Windows 11 servicing model (checkpoint cumulative updates) means offline installers may include SSU and LCU components. When deploying manually, administrators should confirm prerequisites for offline images and follow Microsoft guidance for ordering MSU application where necessary. The Microsoft guidance emphasizes using the Update Catalog and DISM or WUSA appropriately. (learn.microsoft.com, support.microsoft.com)
• Bandwidth and caching: Expect multi-gigabyte payloads on distribution points. Plan for network scheduling and peer caching (Delivery Optimization) where possible to reduce peak bandwidth usage.
• Feature gating and variability: Many of the AI-facing features are gated server-side or by entitlement/hardware (Copilot+). That increases the diversity of experience across a managed fleet on the same build number. Pilot testing and targeted telemetry collection remain essential before broad rollouts. (windowscentral.com)
• Privacy and compliance: New features that capture snapshots or surface recent activity (Recall) raise compliance questions in regulated environments. Evaluate whether to allow those features on corporate devices, configure group policies or MDM controls, and update privacy notices. Microsoft and community reporting stress that Recall is optional and should be controllable at the IT policy level, but teams must validate controls in their environment. (windowslatest.com, windowscentral.com)

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Strengths: why this update matters​

• Quality-of-life wins: Restoring the larger calendar flyout clock, re-introducing seconds in certain Notification Center variants, and polishing taskbar behaviour address long-standing user complaints and reclaim small productivity wins. These changes have outsized perceived value for many users. (windowslatest.com)
• AI integration in the shell: Bringing common image edits and lookups into File Explorer and adding guided tutorials to Click to Do can meaningfully shorten routine workflows, especially for content creators and knowledge workers. These are pragmatic applications of AI—shortcutting existing app flows rather than imposing a completely new interface. (windowscentral.com)
• Security maintenance: The update is mandatory and includes critical security fixes. Applying the patch avoids leaving systems exposed to patched vulnerabilities—arguably the primary reason to keep Windows Update enabled. (windowslatest.com)

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Risks and trade-offs​

• Installer bloat and bandwidth: The inclusion of on-device AI model binaries inflates monthly cumulative installers dramatically. This impacts low-bandwidth environments and increases the cost and time of manual updates. IT teams must adapt distribution strategies accordingly. (windowslatest.com, windowscentral.com)
• Feature fragmentation: Server-side gating and entitlement checks mean that even after patching, user experiences will differ across devices on the same build. That can complicate helpdesk workflows and documentation. (windowscentral.com)
• Privacy surface area: Features like Recall, which capture snapshots of activity, expand the OS’s access to users’ on-screen content. Although opt-in, these features require careful policy, transparency, and user education to avoid privacy surprises in enterprise settings. (windowslatest.com)
• Hardware and firmware dependencies: The SSD reports tied to pre-release firmware underscore a recurring risk: an OS update can expose latent hardware or firmware issues that weren’t visible in prior workloads. Ensuring firmware is production-grade and tested is now a non-trivial part of patch planning. (tomshardware.com, bleepingcomputer.com)

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Actionable recommendations​

• Back up critical systems and data before applying multi‑gigabyte cumulative updates, especially on devices with older or non-standard firmware.
• For home users: let Windows Update handle the patch normally unless you need an offline .msu for a specific reason—Windows Update will stage and install the update automatically. If using the .msu from Microsoft Update Catalog, be prepared for a nearly 4 GB download for x64. (windowslatest.com)
• For IT teams:
• Stage KB5065426 in a pilot ring and validate feature exposure across hardware classes (Copilot+, standard laptops, ARM machines).
• Pre-populate distribution points and peer cache servers to mitigate peak bandwidth.
• Check SSD firmware release notes for vendor advisories and update any drives running pre-release firmware to production firmware before large pilot rollouts. (tomshardware.com, learn.microsoft.com)
• If concerned about Recall or related AI features, validate the feature name locally with DISM (DISM /Online /Get-FeatureInfo /FeatureName:Recall or check the feature listing) before issuing a disable command; confirm exact syntax in Microsoft docs or by enumerating features to avoid mis-typed commands. Do not copy-and-paste unverified commands from third-party posts without verification. (answers.microsoft.com, windowslatest.com)
• Document any differences users may see after updating (e.g., new permission prompt behavior, taskbar clock display) so helpdesk scripts can quickly triage UI questions versus true regressions. (windowslatest.com)

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Final analysis: balancing polish, AI, and manageability​

KB5065426 is emblematic of Microsoft’s current Windows strategy: fuse incremental UX restorations (taskbar clock, calendar flyout) with early-stage on-device AI capabilities that promise real productivity improvements. For users who benefit from the AI features and own Copilot+ hardware, the changes present tangible shortcuts. For IT administrators, however, the update magnifies operational complexity—gigabyte-scale offline installers, firmware dependencies, and feature-gating that fragments end-user experiences across identical builds.
The trade-offs are clear:

• Users gain convenience and new AI-driven workflows.
• Administrators and bandwidth-constrained users incur larger downloads and must add firmware checks to pre-deployment testing.

The prudent path is cautious, measured adoption: pilot widely, update firmware proactively, and rely on Windows Update for most consumer devices while using the Microsoft Update Catalog for targeted offline installs when required. Backups and a firm understanding of which machines qualify as Copilot+ will reduce surprises.
KB5065426 is not an emergency for most users, but it is one of those updates that deserves attention for its operational implications. The return of small, appreciated UI features—combined with the front-loading of AI model payloads—marks another step in Windows 11’s evolution toward blended UI/AI experiences. Whether that evolution is worth the bandwidth and management cost will depend on each organization’s priorities and tolerance for heterogeneity in feature exposure. (windowslatest.com, windowscentral.com)

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Conclusion
KB5065426 (Build 26100.6584) is a substantial servicing package: it fixes and polishes visible UX gaps while carrying heavy AI model payloads that expand the platform’s capabilities. The features are welcome, but the delivery model and size demand updated deployment practices—firmware verification, broader pilot testing, and revised bandwidth planning. Review the update in your pilot ring, verify firmware and backup status, and prepare distribution infrastructure for multi‑gigabyte cumulative packages before broad rollout.

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Source: WindowsLatest Windows 11 KB5065426 24H2 out with taskbar features, direct download links (.msu)