September 2026 Windows 11 KB5124010 Preview Update: New Features, Fixes and Installation Guide

Microsoft released KB5124010, the September 2026 non-security cumulative preview update for Windows 11 versions 26H2, 25H2 and 24H2. The update introduces improvements to File Explorer, Bluetooth, touchpad gestures, accessibility, personalization and other Windows components. It also fixes several reported problems, including issues affecting the built-in camera, File History and Sysmon.

KB5124010 produces OS build 26300.9550 on Windows 11 26H2, 26200.9550 on 25H2 and 26100.9550 on 24H2. It is a non-security preview update, rather than the regular monthly security update.

KB5124010: Update Overview

Property	Details
Update number	KB5124010
Release	September 2026 non-security preview update
Initial release date	September 22, 2026
26H2 applicability added	September 29, 2026
Update type	Cumulative preview update (non-security)
Windows 11 versions	26H2, 25H2 and 24H2
26H2 OS build	26300.9550
25H2 OS build	26200.9550
24H2 OS build	26100.9550
Servicing stack update	KB5124009 (Build 26100.9539)
Installation	Windows Update or Microsoft Update Catalog
Restart	Required to complete installation when prompted

What Is Windows 11 KB5124010?

KB5124010 is a cumulative preview update that delivers non-security improvements, new features and fixes for supported Windows 11 versions. Preview updates allow users and IT administrators to receive and evaluate improvements before they are included in a subsequent regular security update.

Microsoft initially released this update for Windows 11 versions 24H2 and 25H2 on September 22, 2026. On September 29, Microsoft updated its documentation to include version 26H2.

The update is cumulative. If previous updates are already installed, Windows generally downloads and installs only the changes that are still missing.

Windows 11 KB5124010: OS Builds by Version

Windows version	OS build after update	Release date
Windows 11 26H2	26300.9550	September 29, 2026
Windows 11 25H2	26200.9550	September 22, 2026
Windows 11 24H2	26100.9550	September 22, 2026

These build numbers are useful when checking whether KB5124010 has been installed. The appropriate build depends on the Windows version already running on the computer.

To check your version and build, press Windows + R, enter winver and press Enter. Alternatively, open Settings > System > About.

What's New in Windows 11 KB5124010?

KB5124010 introduces a range of improvements. Some features are delivered gradually, so they may not appear on every eligible computer immediately after installing the update.

1. File Explorer Improvements

File Explorer receives several changes intended to improve everyday file management.

• Improved preview handling: Non-HTML files, such as PDFs downloaded from the internet, can be previewed automatically. For HTML files, a Preview anyway button allows users to acknowledge the warning before previewing.
• Remembered Home sections: File Explorer Home remembers whether its sections were expanded or collapsed, preserving the preferred layout.
• More reliable cloud thumbnails: Thumbnail previews for cloud files in the Details pane have been improved.
• Improved Details pane: File properties have been reorganized to make information easier to locate.
• Address bar correction: An issue that could clear address bar text when entering edit mode by clicking near its right side has been addressed.

These improvements are particularly useful for users who frequently manage local files, downloaded documents and cloud-synchronized content.

2. New Emoji and Updated Designs

The update adds support for additional emoji, including distorted face, fight cloud and hairy creature. It also refines several existing emoji designs for better consistency.

To open the emoji panel, press Windows + . (period) on your keyboard.

3. New Tips Widget

Windows 11 introduces a Tips widget that provides short guidance about Windows features.

To add it, open the Widgets board, select Add widgets and choose Tips. You can also add it to the lock screen through Settings > Personalization > Lock screen, where supported.

4. Desktop Personalization Improvements

KB5124010 includes several improvements to desktop background settings and wallpaper handling.

• Improved reliability of the Background page in Settings.
• Support for using DIB image files as desktop backgrounds.
• More reliable desktop slideshow transitions on newly created accounts.
• Improved wallpaper preview resolution.
• Better background previews on portrait-oriented monitors.
• Improved processing of wallpaper changes made in quick succession.
• Support for slideshow wallpapers across multiple virtual desktops without automatically switching the background setting back to Picture.

5. Bluetooth Connectivity and Audio Improvements

The update contains several Bluetooth enhancements that address connectivity, audio and Settings reliability.

• The Windows volume flyout now provides visual feedback when users adjust the volume using supported Bluetooth Classic Audio accessory controls during voice calls.
• Bluetooth connection status is more accurately displayed for disconnected accessories.
• The Bluetooth & devices page in Settings is more stable when managing Bluetooth and audio devices.
• An issue where the Bluetooth radio was switched off while its Settings toggle incorrectly appeared on has been fixed.
• Microphone compatibility with certain Bluetooth Classic audio accessories has been improved.
• A crash with error code 0x139 during Bluetooth audio streaming has been addressed.
• Reliability and performance with Bluetooth LE Audio accessories have been improved.

6. Accessibility Improvements

A new Open apps maximized setting is available under Settings > Accessibility > Visual effects. It automatically maximizes application windows when they open.

This option can be useful for people who prefer a consistent maximized workspace, including users working with screen readers, magnification or tablet mode.

Navigation of the Bluetooth quick settings page has also been improved for keyboard, gamepad and Narrator users.

7. Magnifier Toolbar Refresh

The Magnifier taskbar and toolbar receive a visual update, including redesigned icons and refined spacing. Existing zoom controls, views, keyboard shortcuts and Read Aloud functionality continue to work as before.

8. Settings Improvements

The update improves several areas of the Windows Settings application.

• Improved reliability of the Printers & Scanners page.
• Packaged applications now show their version numbers at the top level of Installed apps.
• The time picker reflects the preferred 12-hour or 24-hour format in supported areas, including active hours and Night light scheduling.
• Improved persistence of the setting that allows multiple applications to use a camera simultaneously.

9. Additional Touchpad Gestures

More gesture controls are available for supported precision touchpads under Settings > Bluetooth & devices > Touchpad.

• Single-finger scrolling: Scroll vertically using one finger starting from the left or right side of the touchpad.
• Automatic scrolling: Continue scrolling without lifting your fingers by moving them near the touchpad's edge while scrolling.

Availability depends on touchpad hardware and driver support.

10. Remapping the Copilot Key

KB5124010 introduces a Windows 11 setting that allows users to remap the dedicated Copilot key to function as the Right Ctrl or Context Menu key. This helps users retain familiar keyboard shortcuts and workflows.

11. Camera Roll Backup

A Camera roll backup option is introduced in Settings for eligible users. It helps users protect their photos through OneDrive, with setup available from Settings Home or Accounts and a QR code workflow on a mobile phone.

Availability depends on device and market eligibility. OneDrive setup and any applicable storage limits still apply.

12. Font Improvements

The Ebrima font gains support for the Garay and Beria Erfe scripts. The update also refines Adlam glyph designs to improve consistency with the current Unicode standard.

13. Windows Recovery Improvements

The update adds a recovery remote management plug-in to extend Windows Recovery Environment (WinRE) management capabilities for mobile device management (MDM) providers.

14. Kiosk Mode Changes

Some keyboard shortcuts are now disabled in restricted kiosk configurations:

• Windows + Tab is disabled in restricted UX kiosk mode.
• Windows + A and Windows + C are disabled in single-app kiosk mode.

These changes help keep kiosk devices within their intended user experience.

15. Windows Backup Changes

The earlier Windows Backup feature that transferred files and settings directly from a previous PC during setup is no longer available. Microsoft directs users to Windows Backup for supported backup and restoration tasks when moving to a new computer.

16. Power and Battery Improvements

The update improves display and performance in certain situations where a plugged-in laptop incorrectly detects a transition from AC power to battery power.

Important Bug Fixes in KB5124010

In addition to new features, Microsoft has included fixes for several issues affecting Windows applications and system components.

Component	Problem addressed
Built-in camera	The camera could stop working in the Camera app and other applications that use it.
File History	Backups or restores to external drives and network locations could fail, sometimes displaying an incorrect Reconnect your drive message.
Sysmon executable validation	Malformed or truncated executable headers could cause unpredictable memory usage and unreliable tampering detection.
Sysmon file system filter	A failed archive-directory open could lead to an uninitialized handle and a stop error.
Sysmon process tampering detection	Incorrect Event ID 25 alerts could be generated for the Windows Session Manager (smss.exe).

Known Issues in Windows 11 KB5124010

Although KB5124010 contains several improvements and fixes, Microsoft has documented issues that may affect some systems. These are particularly important for IT administrators managing business computers.

1. Black Screen or Desktop Loading Problems After Sign-In

Some devices may experience a black screen or desktop loading problems after installing the August 2026 preview update KB5120998 or subsequent updates. The issue has primarily been observed on Azure Virtual Desktop (AVD) hosts using FSLogix, particularly with certain existing user profiles.

Symptoms may include:

• A black screen after signing in.
• The desktop session failing to load automatically.
• Needing to start the desktop session manually.
• Windows Explorer crashes recorded in application event logs.

Temporary workaround: On an affected system, press Ctrl + Shift + Esc to open Task Manager. Select Run new task, enter explorer.exe and select OK. This may temporarily restore the desktop.

For enterprise-managed Windows 24H2 and 25H2 devices, Microsoft also provides a Known Issue Rollback (KIR) policy for administrators. Deploy the appropriate policy and restart affected devices. The workaround temporarily disables the change associated with the issue; it is not a permanent fix.

2. Domain Trust Relationship Problems

Some domain-joined devices using Credential Guard-protected machine accounts may lose their secure trust relationship with an on-premises Active Directory domain after the September 8, 2026 security update KB5124008 or later updates.

Users may receive a trust relationship failure message despite entering valid domain credentials. Cached credentials may still permit offline sign-in.

The issue is associated with Machine Identity Isolation enforcement in environments that do not meet its supported domain requirements.

Microsoft documents workarounds for affected environments, including disabling the unsupported Machine Identity Isolation configuration using the same management method that enabled it. Administrators should first identify whether the setting is managed through Intune, Group Policy or the registry.

For registry-managed systems, follow Microsoft's documented procedure and back up the registry before making changes. After applying the appropriate workaround, a restart and secure-channel repair may be required.

Important: Do not change domain security settings indiscriminately. This issue is relevant primarily to managed Active Directory environments.

3. USB Audio Class 1.0 Devices May Stop Working

Some USB Audio Class 1.0 devices may fail to start or produce sound after the September 8, 2026 security update or subsequent updates.

Possible symptoms include:

• Device Manager displaying error Code 10.
• No audio output.
• Unresponsive volume controls or volume remaining at zero.
• Unresponsive or unavailable sound settings.

The documented issue is limited to USB Audio Class 1.0 devices. Microsoft is working on a resolution. If affected, check the official KB article for the latest guidance rather than applying unrelated driver or registry modifications.

How to Download and Install KB5124010

KB5124010 can be installed through Windows Update or manually using the Microsoft Update Catalog. Windows Update is the simpler method for most home and office users.

Method 1: Install Through Windows Update

1. Press Windows + I to open Settings.
2. Select Windows Update.
3. Select Check for updates, if necessary.
4. Open Advanced options > Optional updates and look for the available preview update.
5. Select the KB5124010 update if it is offered and choose Download and install.
6. Wait for Windows to download and prepare the update.
7. If Windows displays Pending restart, save your work and select Restart now.
8. Allow the computer to finish the installation.

Availability may vary depending on Windows version, hardware, rollout phase and update settings. If the update does not appear, it may not yet be offered to your device.

Method 2: Download from Microsoft Update Catalog

1. Open the Microsoft Update Catalog search for KB5124010.
2. Identify the package matching your Windows version and system architecture.
3. Download the appropriate update package.
4. Check whether the package requires a checkpoint cumulative update. If required and not already installed, install the checkpoint package first.
5. Run the downloaded MSU package and follow the installation instructions.
6. Restart the computer if prompted.

Microsoft's catalog lists separate x64 and ARM64 packages. Do not download a package intended for a different architecture or Windows release.

For managed deployment and offline servicing, follow Microsoft's specific MSU installation instructions, including the required order of checkpoint cumulative updates.

What Does Pending Restart Mean for KB5124010?

If Windows Update shows KB5124010 — Pending restart, it means that a restart is required to finish applying the update.

Before restarting:

• Save open documents and other important work.
• Close applications that may be interrupted.
• Connect laptops to a power source.
• Allow sufficient time for the restart and installation.

Select Restart now in Windows Update. If the restart option is unavailable or you cannot restart immediately, use the scheduling option if Windows provides it.

After signing in again, open Settings > Windows Update and verify the update status. You can also use winver to check the resulting OS build.

Do not force a shutdown simply because the restart takes longer than the estimate shown in Windows Update.

How to Check Whether KB5124010 Is Installed

Check Using Windows Update

1. Open Settings.
2. Select Windows Update.
3. Open Update history.
4. Look for the September 2026 update KB5124010 and check its installation status.

Check Using the OS Build

1. Press Windows + R.
2. Type winver and press Enter.
3. Review the displayed Windows version and OS build.

The expected builds for KB5124010 are 26300.9550 for 26H2, 26200.9550 for 25H2 and 26100.9550 for 24H2. However, an OS build alone may not identify every installed component or subsequent update. Check Update history for the KB number.

Should You Install KB5124010?

KB5124010 is a preview update, so it is intended to deliver non-security improvements and fixes ahead of subsequent regular releases. Whether to install it immediately depends on your requirements.

Situation	Consideration
Personal computer	Consider installing it if you need its improvements or fixes and can accommodate a restart.
Business workstation	Evaluate application compatibility and back up important data before installation.
AVD or FSLogix environment	Review the documented black-screen issue and Microsoft's mitigation guidance before deployment.
Active Directory environment	Review the domain trust issue if Machine Identity Isolation is configured.
USB Audio Class 1.0 hardware	Check the known audio issue if the device is business-critical.
IT-managed computers	Test the update on representative devices before broad deployment.

Important Information for Windows 11 24H2 Users

KB5124010 is the final non-security preview update for Windows 11 version 24H2. Supported editions continue to receive monthly security updates according to their servicing lifecycle.

Windows 11 24H2 Home and Pro editions reach the end of updates on October 13, 2026. Enterprise and Education editions have a later servicing end date of October 12, 2027. Users and administrators should check their specific edition and plan an upgrade where required.

Installing KB5124010 does not extend the servicing lifecycle of Windows 11 24H2.

Official Microsoft References

• Microsoft KB5124010 release notes, features, fixes and known issues
• Windows 11 release information and OS build history
• Microsoft Update Catalog — KB5124010

Frequently Asked Questions

1. What is KB5124010 in Windows 11?

KB5124010 is the September 2026 non-security cumulative preview update for Windows 11 versions 26H2, 25H2 and 24H2. It includes new features, reliability improvements and bug fixes.

2. What is the OS build for KB5124010?

The update produces build 26300.9550 on Windows 11 26H2, 26200.9550 on 25H2 and 26100.9550 on 24H2.

3. Is KB5124010 a security update?

No. It is a non-security preview update. Its improvements and fixes may be incorporated into subsequent regular security updates.

4. When was KB5124010 released?

Microsoft initially released it on September 22, 2026, for 24H2 and 25H2. Version 26H2 was added to its applicability on September 29, 2026.

5. Is KB5124010 available for Windows 11 26H2?

Yes. Microsoft lists KB5124010 for Windows 11 26H2 with OS build 26300.9550.

6. What are the main new features in KB5124010?

The update includes File Explorer improvements, new touchpad gestures, Bluetooth enhancements, accessibility changes, a Tips widget, personalization improvements and additional settings.

7. Does KB5124010 fix File History backup problems?

Yes. It addresses a problem that could prevent File History from backing up or restoring files to external drives or network locations and could produce an incorrect Reconnect your drive message.

8. Does KB5124010 fix camera problems?

Yes. It addresses an issue in which the built-in camera could stop working in the Camera app and other applications.

9. Does KB5124010 fix Bluetooth problems?

It includes several Bluetooth reliability and compatibility improvements, including fixes for incorrect radio status, audio streaming crashes and certain accessory compatibility problems.

10. Is KB5124010 a mandatory update?

It is a non-security preview update and is generally offered as an optional update. Availability and installation behaviour depend on device configuration and update policies.

11. Why does KB5124010 show Pending restart?

Windows needs a restart to finish applying the update. Save your work and select Restart now or schedule the restart if that option is available.

12. How long does KB5124010 take to install?

The duration varies by device, storage speed, update state and system configuration. Windows Update may display an estimate, but actual installation time can differ.

13. Does KB5124010 require a restart?

A restart is required when Windows Update indicates that one is needed to complete installation. Follow the restart prompt and allow Windows to finish.

14. Can KB5124010 cause a black screen?

Microsoft documents black-screen and desktop-loading issues affecting some devices, particularly Azure Virtual Desktop hosts using FSLogix. Consult the official known-issues guidance if you encounter this problem.

15. Can KB5124010 affect Active Directory domain sign-in?

Some domain-joined devices with particular Machine Identity Isolation configurations may experience secure trust relationship failures. This issue primarily concerns managed domain environments.

16. Does KB5124010 affect USB audio devices?

Microsoft documents a problem affecting some USB Audio Class 1.0 devices, which may display Code 10, produce no audio or have unresponsive volume controls.

17. Can I download KB5124010 manually?

Yes. You can search for KB5124010 in the Microsoft Update Catalog and download the package matching your Windows version and architecture.

18. How can I verify that KB5124010 is installed?

Check Settings > Windows Update > Update history for KB5124010. You can also use winver to inspect the Windows version and OS build.

19. Does KB5124010 extend Windows 11 24H2 support?

No. It is the final non-security preview update for 24H2. It does not extend the servicing lifecycle. Windows 11 24H2 Home and Pro reach the end of updates on October 13, 2026.

20. Should businesses install KB5124010 immediately?

Businesses should assess compatibility and review Microsoft's known issues before broad deployment. Testing the update on representative systems is particularly important for AVD, FSLogix and Active Directory environments.

Final Recommendation

KB5124010 brings a substantial set of usability improvements and fixes to Windows 11 versions 26H2, 25H2 and 24H2. Its File Explorer, Bluetooth, touchpad and accessibility improvements may be useful to everyday users, while the camera, File History and Sysmon fixes address specific technical problems.

Before deploying the update across business computers, review the documented black-screen, domain trust and USB audio issues, particularly if your environment uses the affected technologies. For individual computers, install it through Windows Update when appropriate, save your work before restarting and verify the resulting update status.

For the latest installation guidance and known issues, refer to Microsoft's official KB5124010 release notes.