Microsoft has fixed a known issue that stopped some Windows 11 users from switching on its Smart App Control security feature after they installed the October 2026 KB5127648 security update. The problem affected devices running Windows 11 24H2 and later, where the option to enable Smart App Control in the Windows Security app appeared grayed out and could not be toggled.
Smart App Control relies on Microsoft's code integrity features and app intelligence services, and it runs alongside SmartScreen and Microsoft Defender to block potentially harmful apps or binaries. When Microsoft acknowledged the issue last month, it said the problem only hit devices where the feature had been turned off. Machines that already had Smart App Control enabled were not affected and remained protected, according to the company's KB5127648 advisory.
Microsoft confirmed the fix on Wednesday, saying the issue was resolved by Windows updates released October 28, 2026 and later. In a service alert sent to IT administrators, the company recommended installing the latest security update, which it said contains important improvements and issue resolutions, including this one.
For administrators who do not want to deploy this month's KB5127936 preview update on enterprise-managed devices and would rather wait for next month's Patch Tuesday cumulative updates, Microsoft offered a temporary workaround. It requires editing the registry on affected Windows 11 machines to restore the ability to turn on Smart App Control, using two commands at the command prompt followed by a device restart.
Admins can also work around the issue by installing Group Policy settings that turn on Smart App Control and enable logging for troubleshooting. Those settings are found under Computer Configuration, Administrative Templates, in the Windows 11 version 24H2 and 25H2 policy area, and must be set to Enabled after installation. Affected devices must then be restarted for the policy settings to apply.
The KB5127936 preview update also addresses other problems beyond Smart App Control. According to Microsoft, it resolves Remote Desktop failures caused by recent Windows updates when the Administrator protection security feature is enabled, and it finally fixes Always On VPN issues triggered by the September 2026 cumulative updates.
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