Windows 11 update KB5089573: Shared audio & partition fix

Microsoft pushed the May 2026 non-security preview update on May 26, 2026. KB5089573 moves Windows 11 24H2 and 25H2 to OS builds 26100.8524 and 26200.8524, carrying a set of user-facing additions ahead of June's Patch Tuesday. It also surfaces a known issue tied to the earlier May security update that will catch anyone running Windows 11 on hardware with a cramped boot partition.

What's new in KB5089573

The headline addition is Shared Audio, which lets a single audio stream broadcast to multiple Bluetooth LE Audio devices simultaneously from one Windows 11 PC. Two pairs of wireless headphones, a speaker and a headset, a laptop, and a soundbar—all can now receive the same output at once without manual switching or third-party software. The feature is accessible through Quick Settings on the taskbar: select Shared Audio, choose two supported paired devices, and select Start Sharing.

Multi-app camera support arrives alongside it. Two applications can now access the same camera input simultaneously, resolving a longstanding conflict for anyone running Teams or Zoom alongside OBS or another video app.

Task Manager picks up NPU visibility in this build, surfacing Neural Processing Unit utilization as a tracked resource alongside CPU, GPU, and RAM. Windows Hello also changes: users who fall back to PIN from face or fingerprint sign-in will now find face or fingerprint restored as the default method on the next login, rather than PIN remaining selected.

Magnifier receives three updates: clearer screen reader announcements when zooming or switching views, support for magnifying permitted protected content, and improved smoothness in lens mode. Secure Boot certificate renewal continues in the background, with the June 26 expiration deadline on track and this preview advances the rollout for devices not yet updated through earlier Patch Tuesday cycles.

The ESP partition problem

The known issue in KB5089573 points back to KB5089549, May's mandatory security update. Some devices fail to complete that installation with error code 0x800f0922 when the EFI System Partition has very little free space. Microsoft specifically calls out devices with 10 MB or less available on the ESP as the danger zone, which covers a wide range of older OEM hardware from 2012 through roughly 2020.

Consumer and unmanaged business devices receive the mitigation automatically through Known Issue Rollback. Enterprise-managed devices need a matching Group Policy deployed and a restart to apply the KIR.

Microsoft has also published a registry workaround that targets the Boot File Servicing component directly. Running the following command from an elevated Command Prompt sets the ESP padding percentage to zero, eliminating the space buffer the servicing layer demands during installation: reg add "HKLM\SYSTEM\CurrentControlSet\Control\Bfsvc" /v EspPaddingPercent /t REG_DWORD /d 0 /f

Apply this step only to confirmed affected machines. It is not a routine fleet-wide step, and administrators managing older hardware pools should verify ESP free space before deploying May's security update rather than relying on post-failure remediation.

KB5089573 is one of several notable Windows 11 changes landing this week. Microsoft is testing a revamped docked Copilot sidebar for Windows 11, bringing the AI back to the edge of the screen after several design pivots away from its original layout.