A Windows 11 patch meant to fix one bug just created a worse one.
Microsoft has confirmed that KB5124010, the September preview update for Windows 11 24H2, 25H2, and 26H2, breaks apps and games that decode AC-3 (Dolby Digital) audio. Affected titles either fail to launch or crash mid-session, and Reddit threads name Fallout: New Vegas, Elder Scrolls IV: Oblivion, and Wardogs among the casualties. Some users report worse symptoms: boot failures, sluggish shutdowns, and a desktop that grinds to a halt. Microsoft says a fix is coming in a future update but has given no timeline, and the only current workaround is uninstalling the patch entirely.
The timing makes this more than a minor annoyance. KB5124010 is set to become part of October's mandatory update in about a week, and it's also the same patch that fixes a separate bug that broke Windows 11's backup feature back in September. Anyone who grabbed it to repair that backup problem may have walked straight into a new one.
If you've enabled "get the latest updates as soon as they're available," this is a good week to turn that off and let someone else find the bugs first.