Microsoft has confirmed a known issue in Windows 11 security update KB5127648 that can prevent users from re-enabling Smart App Control after it has been turned off.
On affected devices, the Smart App Control setting in Windows Security is grayed out. Devices where the feature was already enabled are not affected and remain protected, according to the KB5127648 release notes.
Smart App Control is a Windows 11 security feature that uses Microsoft’s app intelligence and code-integrity services to help block potentially harmful applications and binaries, alongside Microsoft Defender and SmartScreen, BleepingComputer reports.
Microsoft says it is working on a resolution and will provide an update in an upcoming release. Enterprise administrators should follow its complete Smart App Control workaround instructions for the Group Policy or registry option, including the required values and restart steps. The registry instructions reference HKLM\SYSTEM\CurrentControlSet\Policies\Microsoft\FeatureManagement\Overrides; that location alone is not a complete fix.
Microsoft advises backing up the registry before making changes. KB5127648 also includes security improvements and fixes for issues affecting Windows Explorer, Always On VPN, Storage Spaces Direct and other components.
Correction: The registry path formatting has been corrected. The workaround now links to Microsoft’s complete instructions instead of presenting a partial procedure.