Microsoft said on its Windows release health page that some apps might close unexpectedly after Windows updates released September 22, 2026 (KB5124010) and later. These apps need Windows' built-in decoding of AC-3 (Dolby Digital) audio. BleepingComputer reported that Microsoft confirmed it over the weekend. Microsoft said games, media players and certain work apps can be affected. Some fail to launch; others work until a feature such as music playback is used.
Microsoft has not said how many users are affected or which apps are hit, and gave no date for a fix. A decoder is software that turns compressed audio into sound. Microsoft said many modern apps are fine because they bring their own, while older apps lean on the one built into Windows. BleepingComputer said KB5124010 is an optional preview update, but it installs by itself on Windows 11 24H2 devices with "Get the latest updates as soon as they're available" switched on.
Apps can quietly lean on parts of Windows, so changing that part can break them. Teams can ask vendors whether their apps bundle their own decoder and check that update toggle. Skipping the optional update is a judgement call, since Microsoft says later updates are also affected.