Microsoft confirmed over the weekend that some games and applications using AC-3 (Dolby Digital) audio decoding will crash after installing the September 2026 KB5124010 Windows 11 preview update.

KB5124010 is an optional update that requires users to click the "Download and install" link, which should reduce the number of potentially affected Windows users. However, it installs automatically on devices running Windows 11 24H2, where the "Get the latest updates as soon as they're available" option is toggled on.

"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. "Affected applications may vary and can include games, media players, and certain productivity applications."

However, the company added that many modern apps don't use Windows for this type of encoding and aren't affected. Additionally, the code component that triggers these crashes is most commonly used in legacy applications that still use the Windows built-in audio decoding, while modern apps that use the legacy AC-3 codec often include their own audio decoding components.

Although it didn't provide an estimated timeline for a fix, Microsoft is working to resolve this issue and said it will share more information in a future update.

Last month, Microsoft released emergency updates to fix another known issue causing USB audio issues, as well as Remote Desktop Services failures and Hyper-V problems after installing the KB5124008 and KB5124012 September 2026 security updates.

Last year, the company addressed a similar issue in January that triggered audio playback issues and Code 10 errors on Windows 11 24H2 systems with USB audio device drivers, and lifted a safeguard hold that prevented upgrades and caused Bluetooth headsets and speakers to malfunction on systems with Dirac audio improvement software.

Two years ago, it also confirmed an issue that caused game audio to unexpectedly increase to full volume when using USB DAC sound systems and blocked Windows 24H2 upgrades on systems with incompatible Intel Smart Sound Technology (SST) audio drivers because of blue screen of death (BSOD) issues.

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