Microsoft Windows 11 update bug prevents Smart App Control activation

A bug in the Windows 11 October security update (KB5127648) is preventing some users from re-enabling Smart App Control. The issue affects Windows 11 versions 24H2, 25H2, and 26H2, causing the activation option to appear greyed out for users who previously had the feature disabled.

Microsoft has confirmed that devices with Smart App Control already enabled are not affected and remain protected. The feature is designed to block potentially harmful or unsigned applications by evaluating app services and code integrity.

While a permanent fix is being tested in the Release Preview channel via update KB5127936, it is not yet available to all users. Temporary workarounds involve modifying the Windows Registry through specific command prompts, though users are advised to back up their registry before attempting these changes.