"In some cases the application can fail to launch, or close without warning. In other cases the application will work normally until certain features are used, such as playing music," Microsoft said in a Friday update to the Windows release health dashboard.
What Microsoft has acknowledged
Microsoft confirmed over the weekend that a September 2026 preview update for Windows 11, identified as KB5124010, can cause some games and applications to crash when those programs rely on AC‑3 (Dolby Digital) audio decoding. The company said affected programs may fail to launch, terminate without warning, or run normally until specific audio features—such as playing music—are invoked.
Which applications and code paths are implicated
The crashes are tied to the Windows built‑in audio decoding component used for legacy AC‑3 playback. Microsoft noted that many modern applications do not use Windows for this type of encoding and therefore are not affected. The firm added that the problematic code is most commonly used by legacy applications that rely on the built‑in Windows audio decoder; conversely, many modern apps that still use the legacy AC‑3 codec include their own audio decoding components and are less likely to experience the failure.
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Fix the backlogHow the update is delivered and who might get it
KB5124010 is an optional preview update that requires users to click a "Download and install" link, a distribution choice Microsoft said should reduce the number of potentially affected Windows users. There is an important exception: on devices running Windows 11 24H2, the preview update will install automatically when the "Get the latest updates as soon as they're available" option is toggled on, meaning some 24H2 systems may receive the update without a manual download step.
Where this sits in Microsoft's recent update history
Microsoft is working to resolve the KB5124010 crashes but did not provide an estimated timeline for a fix, and said it will share more information in a future update to the Windows release health dashboard. The company has moved quickly on related audio and platform issues in recent months: last month Microsoft released emergency updates to address USB audio issues, Remote Desktop Services failures, and Hyper‑V problems tied to the September 2026 security updates (KB5124008 and KB5124012).
Microsoft's statements also place KB5124010 within a pattern of prior audio- and upgrade-related safeguards. In January of the previous year the company addressed an issue that triggered audio playback problems and Code 10 errors on Windows 11 24H2 systems with USB audio device drivers, and lifted a safeguard hold that had been preventing upgrades and causing Bluetooth headset and speaker malfunctions on systems with Dirac audio improvement software. Two years ago Microsoft confirmed a separate issue that caused game audio to spike to full volume on USB DAC systems and blocked Windows 24H2 upgrades on systems with incompatible Intel Smart Sound Technology (SST) audio drivers because of blue screen errors.
How end users, developers, and IT administrators are positioned
- End users: Many modern apps are unlikely to be affected because they do not use Windows for AC‑3 decoding; however, devices running Windows 11 24H2 with the "Get the latest updates as soon as they're available" option enabled may receive KB5124010 automatically.
- Application developers and game studios: Legacy applications that rely on the Windows built‑in AC‑3 decoder are the most common users of the implicated code path and therefore the most likely to see crashes tied to this update.
- IT administrators and support teams: The optional nature of KB5124010 should limit blanket exposure, but 24H2 systems with the automatic preview update setting enabled may need tracking and issue triage while Microsoft works on a fix.
Microsoft has committed to further updates on the Windows release health dashboard but has not provided a timeframe. For now, the company’s notices place KB5124010 within a recurring series of audio‑related update disruptions and rapid emergency patches—an operational pattern that will be familiar to teams that manage Windows upgrades and multimedia applications.
Source: BleepingComputer — Microsoft: Windows KB5124010 update crashes some games and apps
