Microsoft Fixes Windows 11 Smart App Control Activation Issue

Microsoft has resolved a technical issue that prevented some Windows 11 users from activating the Smart App Control security feature following a recent update.

The bug was introduced by the October 2026 KB5127648 security update. On affected devices running Windows 11 version 24H2 or later, the Smart App Control option appeared greyed out within the Windows Security app, making it impossible for users to toggle the feature on.

Smart App Control is a security mechanism that utilises Microsoft’s code integrity features and app intelligence services. It works alongside Microsoft Defender and SmartScreen to identify and block potentially harmful applications or binaries from running on a system.

Resolution and Patching

The company confirmed that the issue is resolved in the KB5127936 preview update. Microsoft has recommended that users install the latest security updates to restore the functionality of the feature and ensure comprehensive protection.

Users who already had Smart App Control enabled prior to the October update were not impacted by the bug and remained protected.

Administrative Workarounds

For enterprise administrators who cannot immediately deploy the preview update to managed devices, Microsoft has provided temporary workarounds. These include using specific registry edits or Group Policy settings to restore the ability to enable the feature manually.

The KB5127936 preview update also addresses other recent stability issues, including Remote Desktop failures occurring when “Administrator protection” is enabled and connectivity problems related to Always On VPN that were triggered by previous updates in September 2026.