Windows 11 KB5124010 Can Crash Apps and Games Using AC-3 Audio

Microsoft has confirmed a new Windows 11 issue affecting systems with KB5124010, the September 22, 2026 preview update, and later updates. Applications that require Windows to decode AC-3 (Dolby Digital) audio can close unexpectedly.

Microsoft says the failure depends on what an affected application is doing. Some software can fail to launch or close without warning, while other applications may work until a feature such as music playback invokes the affected decoding path. Microsoft explicitly says affected software can include games, media players and some productivity applications.

KB5124010 applies to Windows 11 versions 24H2, 25H2 and 26H2, with OS builds 26100.9550, 26200.9550 and 26300.9550 respectively. Microsoft's Windows release-health entry lists KB5124010 as the originating update and says the problem applies to updates released September 22, 2026 and later.

That distinction matters because KB5124010 was initially an optional non-security preview. Users who never installed the preview are not necessarily on the affected build yet, while later cumulative servicing can carry the same regression until Microsoft ships a correction.

Microsoft currently lists the issue as confirmed and says it is working on a resolution for a future Windows update. Its release-health notice does not provide a dedicated workaround or a date for that fix.

Users troubleshooting unexplained crashes after KB5124010 should first establish whether the affected application relies on Windows AC-3 decoding before attributing the failure to this bug. Removing an update can also remove unrelated fixes and improvements, so uninstalling KB5124010 is a broader rollback rather than a targeted AC-3 repair.

Core Tech Tips previously covered KB5124010 as Windows 11 24H2's final non-security preview and documented its feature and lifecycle changes. The newly confirmed AC-3 regression is a later support development with a different user intent: diagnosing application or game crashes introduced by the update.

Microsoft opened the AC-3 issue on October 2 and added the known-issue entry to KB5124010's support history on October 3, making the crash behavior newly documented rather than part of the update's original September 22 release notes.