Microsoft has addressed a problem that blocked certain users from turning on Smart App Control following the deployment of the October 2026 KB5127648 Windows 11 security update. The feature integrates Microsoft's code integrity mechanisms and app intelligence systems to work in conjunction with SmartScreen and Microsoft Defender, preventing potentially dangerous applications and binaries from running.
The issue manifested as the Smart App Control toggle becoming unavailable on systems running Windows 11 24H2 and later versions where the feature had been previously disabled. Microsoft acknowledged the problem in its KB5127648 advisory, stating: "After installing this update, some devices might be unable to turn on Smart App Control in the Windows Security app if it has been turned off. On affected devices, the option to turn on Smart App Control might be grayed out. Devices where Smart App Control is already turned on are not affected and remain protected."
The company announced on Wednesday that the fix arrived through the KB5127936 preview update released on October 28, 2026. In a notice to IT administrators, Microsoft stated: "This issue was resolved by Windows updates released October 28, 2026 [..] and later. We recommend you install the latest security update for your device as it contains important improvements and issue resolutions, including this one."
Workaround available
For administrators managing enterprise environments who prefer to defer the preview update until the next Patch Tuesday cycle, Microsoft provided a temporary solution involving registry modifications to restore Smart App Control activation on affected Windows 11 devices.
- Open a Command Prompt window by typing cmd in the Search box.
- Select Run as Administrator.
- At the command prompt, enter the following commands and then restart the device:
reg add "HKLM\SYSTEM\CurrentControlSet\Policies\Microsoft\FeatureManagement\Overrides" /v 2883193997 /t REG_DWORD /d 1 /f reg add "HKLM\SYSTEM\CurrentControlSet\Policies\Microsoft\FeatureManagement\Overrides" /v 2850574478 /t REG_DWORD /d 1 /f
An alternative approach involves deploying specific Group Policies that enable Smart App Control and activate logging for diagnostic purposes:
- Windows 11, versions 24H2, 25H2, and 26H2 - KB5074105 261015_19222 Feature Preview
- Windows 11, versions 24H2, 25H2, and 26H2 - KB5074105 261015_19221 Feature Preview
After installation, administrators should navigate to Computer Configuration > Administrative Templates > {Group Policy name} > Windows 11, version 24H2, 25H2, and configure the settings to Enabled. A device restart is necessary to apply these Group Policy modifications.
Beyond addressing the Smart App Control issue, the KB5127936 preview update also resolves Remote Desktop connection failures that emerged from recent Windows updates when the "Administrator protection" security feature is active, and corrects Always On VPN problems stemming from the September 2026 cumulative updates.