Microsoft has confirmed that a September 2026 Windows 11 preview update is causing crashes in some games and applications that rely on AC-3, or Dolby Digital, audio decoding. The update, KB5124010, was released as an optional preview and requires users to click a "Download and install" link before it is applied, according to a Friday update to the Windows release health dashboard. The company said affected programs may fail to launch or shut down without warning, while others may run normally until specific features, such as music playback, are used.
Because KB5124010 is optional, the pool of potentially affected Windows users should be smaller than it would be for a mandatory release. Microsoft noted, however, that the update installs automatically on devices running Windows 11 24H2 when the "Get the latest updates as soon as they're available" option is turned on. That setting, which is common on consumer PCs in the United States and elsewhere, puts those systems on the update without any user action.
Microsoft said the applications that can be affected vary and may include games, media players, and certain productivity applications. The company added that many modern apps do not depend on Windows for this type of audio encoding and therefore are not affected. The code component responsible for the crashes is most commonly used in legacy applications that still rely on the Windows built-in audio decoding, while modern apps that use the legacy AC-3 codec often ship with their own audio decoding components.
Microsoft said it is working to resolve the issue and will share more information in a future update, but it did not provide an estimated timeline for a fix. The acknowledgment follows a stretch of audio and reliability problems tied to recent Windows updates. Last month, the company released emergency updates to address USB audio issues, Remote Desktop Services failures, and Hyper-V problems that appeared after users installed the September 2026 security updates KB5124008 and KB5124012.
The KB5124010 problem is the latest in a series of audio-related issues Microsoft has addressed on Windows 11 24H2. Last year, the company fixed a January issue that caused audio playback problems and Code 10 errors on systems with USB audio device drivers, and it lifted a safeguard hold that had blocked upgrades and caused Bluetooth headsets and speakers to malfunction on systems running Dirac audio improvement software. Two years ago, Microsoft confirmed an issue that caused game audio to jump unexpectedly to full volume when USB DAC sound systems were used, and it blocked Windows 24H2 upgrades on systems with incompatible Intel Smart Sound Technology audio drivers because of blue screen of death issues.
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