CybersecurityVulnerability Management

Microsoft Releases KB5124010 Update, Bolsters Windows 11 with 46 Fixes

Analyst 207||Source: BleepingComputer
Windows 11 laptop screen on a desk with blurred office background.

Microsoft's September 2026 preview update KB5124010 ships with 46 changes and fixes, delivering a mix of new features, accessibility tweaks and a string of Bluetooth and backup repairs for Windows 11 24H2 and 25H2.

What KB5124010 is and how it fits the update cycle

KB5124010 is an optional, non-security preview update that Microsoft released to let administrators and users test Windows improvements, bug fixes, and new features before those changes are rolled into next month’s Patch Tuesday release. Unlike regular cumulative updates, monthly optional updates such as KB5124010 provide only quality improvements and do not include security fixes. Microsoft said this September preview is the final preview update for Windows 11 24H2, which reaches end of support in October 2026.

New features and settings included in the update

The update adds several user-facing features. It introduces support for Emoji 17.0 and a new "Open apps maximized" accessibility setting that automatically maximizes app windows when they open. Users can now remap the Copilot key through a Windows 11 setting so the key functions as Right Ctrl or the Context Menu key. The update also enables slideshow wallpapers to work across multiple desktops without reverting to a single Picture wallpaper, and it brings additional gesture controls for precision touchpads under Settings > Bluetooth & devices > Touchpad.

KB5124010 also introduces Camera roll backup in Settings to help eligible users protect photos with OneDrive; the feature can be enabled from the Settings Home or Accounts page and completed on a mobile phone using a QR code. In addition, a recovery remote management plug-in was added to extend Windows Recovery (WinRE) management capabilities.

Bluetooth, audio, and backup fixes

Several fixes target Bluetooth behavior and audio stability. Microsoft resolved an issue where the Bluetooth radio could be turned off while the Bluetooth radio control toggle in Settings still showed as on, and a bug that could cause crashes with error code 0x139 while streaming Bluetooth audio. The update improves microphone compatibility with certain Bluetooth Classic audio accessories, and it improves reliability and performance with LE Audio accessories.

On the backup side, Microsoft fixed a known issue that was causing the built-in File History backup feature on some Windows systems to fail after installing the September 2026 security updates. In a separate behavioral change, KB5124010 removes PC-to-PC Migration, a tool that helped users transfer files, settings, and preferences to a new Windows device; Microsoft recommends using Windows Backup to migrate to a new PC via OneDrive.

Builds, installation steps, and distribution options

After installation, the optional update upgrades devices to build 26200.9550 for Windows 11 25H2 and 26100.9550 for 24H2. To install KB5124010 through the OS, open Settings, click Windows Update, and then "Check for Updates." Because the update is optional, users will need to click the "Download and install" link unless they have enabled the "Get the latest updates as soon as they're available" option, in which case the OS will prompt to install automatically. Administrators and users may also manually download and install the KB5124010 preview update from the Microsoft Update Catalog.

What this means for technologists, enterprises, and end users

  • Technologists and security teams: The preview nature and lack of security fixes mean teams can use KB5124010 to validate quality improvements and device compatibility — particularly around Bluetooth and audio stacks — before the changes arrive in the security servicing channel.
  • Enterprises and procurement leaders: Organizations still running Windows 11 24H2 should note that this is the final preview update before 24H2 reaches end of support in October 2026; migration planning and use of Microsoft’s recommended Windows Backup with OneDrive for PC-to-PC migration will be relevant operational steps.
  • End users and device managers: New conveniences — Copilot key remapping, Camera roll backup with OneDrive, and slideshow wallpapers across multiple desktops — are available to test now, but KB5124010 must be explicitly downloaded because it does not include security fixes and is optional.

KB5124010 is a feature-and-quality focused checkpoint: it packages dozens of small user-facing additions and reliability fixes for testing ahead of the regular October servicing. For users on 24H2, it doubles as a last preview before support ends; for others it is a way to trial changes — especially those around Bluetooth, audio, backups, and new UI settings — before they move into the mainstream release cadence.

Source: BleepingComputer — Windows 11 KB5124010 update released with 46 changes and fixes

Emerging ThreatsMicrosoftPatch TuesdayWindows 11Windows UpdateOptional UpdateNon-Security UpdateKB5124010Preview Update
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