It’s October 2026, and Microsoft is still finding bugs in Windows 11’s September updates. We’ve already had a mandatory Patch Tuesday update, an emergency patch, and an optional release, but the problems keep piling up. Now, Microsoft has confirmed that some apps or games could crash if they rely on Windows to decode AC-3 (Dolby Digital) audio.
Microsoft says the bug affects Windows 11 26H2, 25H2, and 24H2 after installing KB5124010, released on September 22, or later updates.
September has been a disaster for Windows. At one point, it had started to look like Microsoft was finally getting a hold of its quality control, and Windows would become stable. But when you look at everything that went wrong last month, you’d wonder if things are moving in the opposite direction.
Windows 11’s September updates fixed some bugs and introduced another
On September 8, Microsoft rolled out KB5124008 with some of the most-requested features, including a movable taskbar, a resizable Start menu, and Bing-free Windows Search.
It also patched hundreds of security vulnerabilities, including multiple remote code execution issues. On paper, it was a great update, and it’s still been a good one for me, but some users have had major issues.
Microsoft acknowledged problems with Remote Desktop, USB audio, and File History backups. Windows Latest also reported black screens and AMD GPU errors, including driver timeouts and freezes. Microsoft still hasn’t confirmed AMD GPU issues, but it hasn’t dismissed them either.
Claude Cowork also lost access to local files because the update broke folder sharing with certain Linux virtual machines.
Microsoft responded on September 14 with KB5129195, an emergency update that fixed Remote Desktop, the folder-sharing problem, and a multichannel audio issue. However, some USB audio devices still wouldn’t work.
Then, Microsoft found another issue in Windows 11 where the built-in backup and restore feature called ‘File History’ wouldn’t work at all and would throw an error that an external drive or network was not configured for files to be backed up. Some users were in for a surprise when they found their files had quietly stopped backing up.
On September 22, Microsoft rolled out the KB5124010 update and told us that audio, as well as File History, should work properly again. However, our testing found that File History still wasn’t fully fixed for everyone, as backup timestamps and file versions have been failing to update.
And now, it turns out that the same Windows update introduced another critical issue, this time causing apps or games to close unexpectedly.
Some apps and games could crash when decoding Dolby Digital audio
As first spotted by Windows Latest, Microsoft has quietly confirmed that some apps and games that use AC-3 (Dolby Digital) audio decoding could crash abruptly or close unexpectedly when you increase your volume, change audio settings, or use some audio features.
Microsoft won’t tell us what audio behaviour is crashing these apps or games, but if you run into sudden performance issues after updating Windows 11, you should either stop using audio or consider turning off features that you might have turned on.
According to Microsoft, it’s not expecting a lot of users to run into the bug because it affects only apps or games that rely on Windows’ built-in audio decoding.
“Incidence of this issue depends on the activity that these applications perform. In some cases the application can fail to launch, or close without warning,” Microsoft explained.
“In other cases the application will work normally until certain features are used, such as playing music. Affected applications may vary and can include games, media players, and certain productivity applications.”
This is separate from September’s USB audio bug, where some audio devices could stop producing sound and show a Code 10 error in Device Manager or make Sound settings unresponsive.
Microsoft insists that most modern apps shouldn’t crash when you play music or audio, but it can’t tell us exactly who is affected at this point.
And yes, as I noted above, Windows 11 26H2 is affected, too. This shouldn’t surprise anyone because 26H2 shares its underlying code with 25H2 and 24H2, so upgrading doesn’t automatically get rid of bugs carried over from those releases.
For now, Microsoft has promised a fix, but it hasn’t given a release date.
“Microsoft is working on releasing a resolution for this issue in a future Windows update. We will provide an update when more information is available,” the company noted.
