Microsoft has released the Windows 11 KB5124010 update, a September 2026 non-security preview build carrying 46 changes across Windows 11 24H2 and 25H2. Among the headliners: Bluetooth reliability improvements, Emoji 17.0 support, and a new setting that lets users remap the Copilot key to something they might actually use more often.
As an optional preview update, KB5124010 gives administrators and keen users the chance to test improvements and bug fixes ahead of their scheduled arrival in next month’s Patch Tuesday cumulative update. The important caveat is that monthly optional updates of this type carry quality improvements only; security fixes are not included.
What the Windows 11 KB5124010 update actually fixes
Bluetooth users will be the most immediately grateful. Microsoft has resolved a particularly annoying bug where the Bluetooth radio could be switched off while the toggle in Settings still cheerfully reported it as on. A separate crash bug, surfacing as error code 0x139 during Bluetooth audio streaming, has also been squashed. On top of those fixes, microphone compatibility with certain Bluetooth Classic audio accessories has been improved, and reliability and performance with LE Audio accessories have been tightened up.
The File History backup feature also gets some attention: Microsoft has fixed a known issue that was causing the built-in backup to fail on some Windows systems after installing the September 2026 security updates. Not the sort of thing you want quietly breaking in the background.
On the accessibility side, a new ‘Open apps maximised’ setting will automatically maximise app windows as they open. A recovery remote management plug-in has also been added to extend Windows Recovery (WinRE) management capabilities.
New features and notable removals
Beyond the fixes, the update introduces a handful of new capabilities. Slideshow wallpapers now work properly across multiple desktops, without flipping users back to a static picture. Additional gesture controls for precision touchpads have been added under Settings > Bluetooth & devices > Touchpad. Camera roll backup, which lets eligible users protect their photos via OneDrive, is now available in Settings, with setup completable on a mobile phone by scanning a QR code.
Then there is the Copilot key remap. After installing KB5124010, Windows 11 users can reassign the Copilot key to function as the Right Ctrl or Context Menu key via a dedicated setting. For anyone who has found the key landing in exactly the wrong place during a sprint across the keyboard, that option will be welcome.
Less welcome, perhaps, is the removal of PC-to-PC Migration, a tool that previously helped users transfer files, settings and preferences to a new Windows device. Microsoft is now pointing users towards Windows Backup with OneDrive as the recommended route for moving to a new PC.
Emoji 17.0 support rounds out the feature additions, for those who have been waiting patiently for whatever the latest round of characters brings.
End of support and install details
Once installed, KB5124010 takes Windows 11 25H2 to build 26200.9550 and Windows 11 24H2 to build 26100.9550. Installation is straightforward: open Settings, navigate to Windows Update, and select ‘Check for Updates’. Because this is an optional update, a manual ‘Download and install’ click is required unless the ‘Get the latest updates as soon as they’re available’ option is already enabled. It can also be downloaded directly from the Microsoft Update Catalog.
Worth flagging for IT teams managing older fleets: Microsoft has confirmed that KB5124010 is the final preview update for Windows 11 24H2, which reaches end of support in October 2026. Anyone still running 24H2 will want to have an upgrade plan in place before that deadline lands, since no further preview updates will be staged ahead of it. Full details on the update are available via Microsoft Support.
