In October 2026, MS is still identifying bugs linked to Windows 11’s September updates. Despite releasing a mandatory Patch Tuesday update, an emergency patch, and an optional update, additional problems continue to emerge. MS has now confirmed that certain apps and games may crash when using Windows to decode AC-3 (Dolby Digital) audio.
The issue affects Windows 11 versions 26H2, 25H2, and 24H2 after installing KB5124010, released on September 22, or any later update.
September proved particularly difficult for Windows. MS had appeared to be improving its quality control and overall system stability, but the number of issues introduced during the month suggests that significant challenges remain.
September Updates Fixed Existing Bugs but Introduced New Problems
On September 8, MS released KB5124008 with several highly requested features, including a movable taskbar, a resizable Start menu, and Windows Search without Bing integration.
The update also addressed hundreds of security vulnerabilities, including several remote code execution flaws. Although it appeared to be a strong release, some users encountered major problems after installing it.
MS acknowledged issues involving Remote Desktop, USB audio, and File History backups. Users also reported black screens and AMD GPU problems, including driver timeouts and system freezes. MS has neither confirmed nor dismissed the reported AMD GPU issues.
Claude Cowork also lost access to local files because the update disrupted folder sharing with certain Linux virtual machines.
MS responded on September 14 with the emergency KB5129195 update. It resolved the Remote Desktop issue, the folder-sharing problem, and a multichannel audio bug. However, some USB audio devices remained unusable.
Another problem affected Windows 11’s built-in backup and restore feature, File History. The tool could stop working entirely and incorrectly report that no external drive or network location had been configured for backups. Some users discovered that their files had silently stopped being backed up.
On September 22, MS released KB5124010, which was intended to correct the audio and File History problems. However, subsequent testing showed that File History was still not fully repaired for every user, with backup timestamps and file versions sometimes failing to update.
The same update has now been linked to another serious issue that may cause certain apps and games to close unexpectedly.
Apps and Games May Crash While Decoding Dolby Digital Audio
MS has confirmed that some apps and games using AC-3 (Dolby Digital) audio decoding may crash or close without warning when users increase the volume, modify audio settings, or activate certain audio features.
MS has not specified which exact audio behavior triggers the crashes. Users who experience sudden application instability after updating Windows 11 may need to avoid audio playback temporarily or disable recently enabled audio features.
The company does not expect the issue to affect a large number of users because it is limited to software that relies on Windows’ built-in audio decoding capabilities.
According to MS, the frequency of the problem depends on what an affected application is doing. In some cases, an app may fail to launch or close without warning. In others, it may operate normally until a particular feature, such as music playback, is used.
Affected software may include games, media players, and certain productivity applications.
This problem is separate from September’s USB audio bug, which could prevent some audio devices from producing sound, display a Code 10 error in Device Manager, or cause the Sound settings page to become unresponsive.
MS maintains that most modern applications should not crash during music or audio playback, although the company has not yet provided a definitive list of affected software.
Windows 11 26H2 is also affected because it shares its underlying code with versions 25H2 and 24H2. As a result, upgrading does not automatically eliminate bugs carried over from those releases.
MS is developing a resolution for a future Windows update, but it has not announced a release date. The company says it will provide further information when it becomes available.
