Windows 11 KB5124008 September 2026 Update: New Features, Improvements and Reported Problems

Quick Answer

Microsoft released KB5124008 on 8 September 2026 as the monthly cumulative security update for Windows 11 versions 25H2 and 24H2. It updates Windows 11 25H2 to OS Build 26200.9445 and Windows 11 24H2 to OS Build 26100.9445.

This is a feature-rich monthly update. Its most visible additions include a taskbar that can be moved to any screen edge, a genuinely smaller taskbar, adjustable Start menu sizes, independent Start menu sections, and controls to disable Bing web and Microsoft Store suggestions in Windows Search. It also improves File Explorer, virtual desktops, VPN reliability, Japanese input, Outlook Search, touchpads, Narrator and update servicing. Enterprise additions include Administrator Protection, Windows Autopilot device association and Process Isolation for Microsoft Execution Containers.

At the time this article was checked on 8 September 2026, no widespread new failure pattern attributable specifically to KB5124008 had been established through reliable public reporting. The update was only hours old, so that status may change. Microsoft-confirmed issues, repeatable reports from multiple users and isolated comments must be treated as three different evidence levels.

KB5124008 Release Information

Item	Details
Update	KB5124008
Release date	8 September 2026
Type	Monthly cumulative security update / Patch Tuesday release
Windows 11 25H2 build	26200.9445
Windows 11 24H2 build	26100.9445
Delivery	Windows Update, managed deployment tools and Microsoft Update Catalog
Restart	Normally required
Related package on some PCs	KB5126052 .NET Framework Security Update

KB5124008 incorporates the applicable changes from the 27 August 2026 optional preview and adds September security fixes. Because it is cumulative, Windows servicing determines the applicable prerequisites and package chain.

Several interface changes use Controlled Feature Rollout. Therefore, two computers on the same OS build may not receive every new option on the same day.

Major New Features in KB5124008

1. Move the Taskbar to Any Screen Edge

Windows 11 can position the taskbar at the top, bottom, left or right of the display. The option appears under:

Settings > Personalization > Taskbar > Taskbar behaviors > Taskbar position

The Start menu, flyouts, tooltips and animations follow the selected position. This restores flexibility that many Windows 10 users missed.

There is a limitation: the full Search box and smaller taskbar variant may currently work only when the taskbar is at the top or bottom. A vertical taskbar may simplify or remove those elements.

2. A Properly Smaller Taskbar

The compact option reduces both the icons and the taskbar’s height. It saves space on laptops and smaller displays, although it may make buttons harder to select on touch devices.

3. Resizable and More Customizable Start Menu

Under Settings > Personalization > Start, Windows can offer three sizes:

• Automatic: Windows selects a size based on the display and configuration.

• Small: Reduces the space occupied by Start.

• Large: Displays more content and consumes more screen area.

Independent controls are available for the Pinned, Recent and All sections. Recommended is renamed Recent. Users can also hide their name and profile picture from Start, which is useful during presentations, recordings and screen sharing.

Hiding a section does not necessarily resize the whole menu; use the dedicated size selector for that.

4. Disable Bing and Microsoft Store Results in Windows Search

Windows Search gains separate controls for web and Microsoft Store suggestions under:

Settings > Privacy & security > Search > Show suggested search results

Turning off Web searches and Microsoft Store suggestions provides a cleaner local-search experience focused on installed apps, settings and indexed files. Search may also feel faster because it is not waiting for online suggestions.

Results receive clearer labels, the interface is less promotional, and typo tolerance is improved. Windows may automatically index frequently used folders; this behaviour can be managed in Search settings.

5. Faster File Explorer and Virtual Desktops

File Explorer Home is designed to load faster and feel more responsive. Its Recommended carousel supports touch scrolling. Virtual desktop transitions also receive responsiveness improvements.

Progress indicators used during startup, sign-in, restart, shutdown and update installation have a more consistent Windows 11 appearance.

Security and Enterprise Changes

Administrator Protection

Administrator Protection moves Windows toward just-in-time elevation. Instead of allowing a process to keep unrestricted administrator rights, Windows creates a temporary isolated administrator token for a specifically approved task and removes it afterward.

This is security hardening, not an absolute security boundary. It may remain disabled by default and is intended for administrator-managed deployment. Organizations should test installers, scripts, management agents and business software before enabling it through supported policy controls.

Windows Autopilot Device Association

Windows Autopilot device preparation adds general availability for device association. Organizations can identify trusted devices before enrolment and apply device-targeted configuration during setup. Home users will generally not notice this change.

Process Isolation for Microsoft Execution Containers

Microsoft Execution Containers gain Process Isolation, a lightweight controlled environment for workloads such as coding agents and model-generated code. Policies can restrict file, network and user-interface access. Preview support also permits agentic processes to carry an opaque identifier into child processes and certain authentication requests.

Post-Quantum TLS Support

ML-KEM can now be used as a standalone algorithm for TLS key exchange. This matters mainly to organizations preparing cryptographic infrastructure for future post-quantum requirements.

WMIC Is Removed

KB5124008 completes removal of the legacy WMIC command-line utility from Windows 11 24H2 and 25H2. Windows Management Instrumentation itself remains supported; the removed component is the wmic.exe wrapper.

An old command such as:

wmic cpu get name

should be replaced by a supported PowerShell/CIM command:

Get-CimInstance Win32_Processor | Select-Object Name

Administrators should audit batch files, login scripts, inventory utilities and support tools for WMIC dependencies. Do not download unofficial WMIC copies or transplant system files from another installation.

Other Improvements and Fixes

Area	Improvement
File Explorer	Faster Home loading and touch scrolling for the Recommended carousel
Windows Share	Work or school accounts can discover relevant apps from Share
VPN	Better resilience when VPN-related background processes stop responding
Wi-Fi reporting	Corrected Japanese output from netsh wlan show wlanreport
Japanese IME	Fixes typing reliability and hanging behaviour
RemoteApp	Japanese text displays correctly while typing
Outlook Search	Corrects the To label and improves Sent Items and Advanced Find on Japanese systems
Voice typing	Remembers automatic punctuation and launcher preferences
Display	More reliable navigation and correct brightness restoration after Energy Saver
Touchpad	Improves gesture and mouse-drag reliability on affected devices
Narrator	More reliable installation and setup of Natural Voices
Task Manager	Displays app-history information more reliably
Sleep	A manually sleeping PC can return to sleep after finishing an update
App updates	Participating apps can coordinate through Windows Update Orchestration Platform
Setup	Secondary keyboard selection is easier to skip
Get Started	Refreshed pages for app installation, site pinning and themes
AI components	Background updates for Image Search, Content Extraction, Semantic Analysis and Settings Model
Servicing stack	Improves Windows update-installation reliability

KB5126052 .NET Framework Security Update

Some PCs receive KB5126052 alongside KB5124008. It services installed Microsoft .NET Framework components used by desktop and business applications. It is separate from modern .NET 8 or .NET 9 updates, which can appear under different KB numbers.

Both packages can wait for the same restart because Windows coordinates reboot-dependent changes. Pending restart is a normal installation stage, not a reported fault.

Known Issues and Problems Reported by Users

Microsoft-Confirmed Problems

As of the research cutoff on 8 September 2026, no newly established, widely applicable problem caused specifically by KB5124008 was identified in the Microsoft information available for this article. This is not a permanent guarantee that the update has no issues. Microsoft can add known issues after receiving telemetry and support cases.

Check the latest Windows 11 release information dashboard and Microsoft Windows Support before large deployments.

Early User Reports

The update had been available for only hours at the research cutoff. There was not enough independent, repeatable evidence to describe isolated installation comments as a widespread KB5124008 defect.

Evidence level	Correct interpretation
Microsoft acknowledgement	Confirmed known issue, including affected configurations and official status
Same repeatable symptom from several credible sources	Emerging user-reported problem, not yet officially confirmed
One comment, video or social post	Isolated report; insufficient evidence to blame the update

The article should be revised if credible patterns emerge involving installation failures, gaming, File Explorer, taskbar behaviour, VPN, printers, Remote Desktop or business applications.

Features Missing After Installation

This is most likely Controlled Feature Rollout rather than an installation failure. A PC may successfully install Build 26200.9445 or 26100.9445 without immediately showing the taskbar-position, Start-menu-size or Search options. Microsoft may enable them over days or weeks.

Avoid ViVeTool, registry hacks and unofficial feature-enablement scripts on production computers simply to bypass staged rollout.

Vertical Taskbar Limitations

The Search box and compact taskbar may not be available in vertical layouts. This is a current design limitation, not proof that the update is damaged.

WMIC “Not Recognized” Message

After updating, an old script may show:

'wmic' is not recognized as an internal or external command

This is expected. Update the script to PowerShell/CIM instead of attempting Windows Update repair.

Should You Install KB5124008?

Home Users

Yes, generally. This is a mandatory cumulative security update with substantial usability improvements. Save work, maintain a current backup and install it through Windows Update.

Business Users

Deploy promptly, but validate on a pilot group first. Test:

• VPN and endpoint security software

• Printing and scanning

• Remote Desktop and RemoteApp

• Accounting and line-of-business applications

• Login, elevation and deployment scripts

• Inventory scripts that may still use WMIC

• Taskbar and Start policies

WMIC removal and Administrator Protection deserve particular attention in managed environments.

How to Install and Verify It

1. Open Settings > Windows Update.

2. Select Check for updates.

3. Install 2026-09 Security Update (KB5124008).

4. Install KB5126052 if Windows offers it for the installed .NET Framework components.

5. Save work and restart normally.

Press Windows + R, enter winver, and press Enter. Windows 11 25H2 should report 26200.9445 or later; Windows 11 24H2 should report 26100.9445 or later.

If the build is correct but new interface features are missing, wait for Controlled Feature Rollout rather than reinstalling Windows.

Basic Troubleshooting

If installation genuinely fails:

1. Record the exact error code.

2. Restart and retry once.

3. Check free disk space and network stability.

4. Run the Windows Update troubleshooter.

5. Open Terminal as administrator and run:

DISM /Online /Cleanup-Image /RestoreHealth
sfc /scannow

DISM repairs the Windows component store; SFC verifies protected system files. Both require administrator rights. Do not interrupt DISM because its percentage can remain unchanged for some time.

Never delete WinSxS, disable Windows Update permanently or download update packages from unofficial sites.

FAQ

What is KB5124008?

It is Microsoft’s September 2026 cumulative security update for supported Windows 11 25H2 and 24H2 installations.

Which builds does it install?

It installs Build 26200.9445 on Windows 11 25H2 and Build 26100.9445 on Windows 11 24H2.

What are the biggest features?

A movable and smaller taskbar, adjustable Start menu sizes, independent Start sections, controls for disabling web and Store Search results, plus performance and reliability improvements.

Can the taskbar be vertical?

Yes. It can be placed on the left or right, although the Search box and compact variant may have limitations.

Can I remove Bing results from Search?

The update introduces separate controls for web and Microsoft Store suggestions. Their availability may be staged.

Why are the features missing after installation?

Microsoft uses Controlled Feature Rollout. Confirm the build and wait for the feature to reach the PC.

Is WMIC removed?

Yes, the legacy command-line wrapper is removed. WMI remains supported; use PowerShell CIM commands.

What is KB5126052?

It is a September 2026 security update for applicable Microsoft .NET Framework components.

Has Microsoft confirmed KB5124008 problems?

At the 8 September 2026 research cutoff, no new widespread issue specific to KB5124008 had been established in the Microsoft material reviewed. The current release-health page should be checked because status can change.

Are users reporting problems?

It was too early to identify a credible repeated pattern. Isolated reports should not be presented as confirmed defects without corroboration.

Is Pending restart an error?

No. It means Windows needs a normal restart to complete installation.

Should businesses deploy it immediately?

Security deployment should be prompt, but critical applications and scripts should first be tested on representative pilot devices.

How do I verify it?

Use winver for the build and check Settings > Windows Update > Update history.

Can it be uninstalled?

Windows may offer removal under Update history > Uninstall updates. Removal also removes security fixes and should be used only for a serious, confirmed problem.

Where can I download it manually?

Use only the Microsoft Update Catalog and select the package matching the Windows version and processor architecture.

Final Recommendation

KB5124008 is one of the more substantial Windows 11 monthly updates of 2026. Its movable taskbar, compact taskbar, adjustable Start menu and cleaner local Search address long-standing usability requests. It also delivers security, servicing, networking, input and enterprise improvements.

Home users should normally install it through Windows Update. Businesses should test critical software and scripts first, especially anything dependent on WMIC, elevation behaviour, VPN, RemoteApp or customized shell policies.

No widespread new KB5124008 failure pattern had been reliably established when this article was checked on 8 September 2026. Because the release was new, continue monitoring Microsoft’s release-health information and credible repeated reports. Do not confuse staged feature availability, intended WMIC removal or a normal pending restart with update failure.

 

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Sources and Verification Date

Information was checked on 8 September 2026 using current release reporting and Microsoft technical resources. Feature and build details are supported by Windows Latest’s KB5124008 release report and its tested feature and fix breakdown. Known-issue status should always be rechecked through Microsoft Windows release