Microsoft has resolved a known issue that caused games and Windows 11 applications relying on AC-3 (Dolby Digital) audio decoding to crash following installation of the September 2026 preview update, KB5124010. The fix arrives in the KB5127648 October 2026 Patch Tuesday update, according to an update posted to the Windows release health dashboard. Affected users on Windows 11 24H2 and later are advised to install it.
The scope of the original problem was limited by how KB5124010 is distributed. The update is optional and requires users to click a "Download and install" link, which reduces the number of potentially affected Windows users. However, it installs automatically on devices where the "Get the latest updates as soon as they're available" option is toggled on.
Microsoft described the symptoms when it acknowledged the issue two weeks ago. In some cases an application fails to launch or closes without warning, while in other cases it works normally until certain features are used, such as playing music. Affected software could vary and include games, media players, and certain productivity applications, Microsoft said.
The company also noted that many modern apps that do not use Windows' built-in audio decoding for this type of encoding are unaffected. Modern apps that use the legacy AC-3 codec often ship with their own audio decoding components, Microsoft added. In its dashboard update, the company recommended installing the latest security update for each device, saying it contains important improvements and issue resolutions, including this one.
The AC-3 crash is the latest in a series of audio-related defects Microsoft has addressed in recent years. Two years ago the company confirmed a bug that caused game audio to unexpectedly jump to full volume when using USB DAC sound systems. It also blocked Windows 24H2 upgrades on devices with incompatible Intel Smart Sound Technology (SST) audio drivers because of blue screen of death (BSOD) issues.
In January 2025, Microsoft addressed a similar issue that triggered audio playback problems on Windows 11 24H2 systems with USB audio device drivers. At the same time it lifted a safeguard hold that had prevented upgrades because an incompatibility issue caused Bluetooth headsets and speakers to malfunction on systems with Dirac audio improvement software. More recently, in September, Microsoft released emergency updates to fix another bug that triggered USB audio issues after installing the September 2026 KB5124008 and KB5124012 security updates.
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