Microsoft’s October 2026 Windows 11 security update KB5127648 may prevent some users from enabling Smart App Control after the feature has been switched off.
The problem affects Windows 11 version 24H2 and later, according to Microsoft information reported by BleepingComputer on October 16, 2026. On affected systems, the control in the Windows Security application is grayed out, leaving users unable to turn the protection back on through the usual interface.
Devices that already had Smart App Control enabled before installing KB5127648 are not affected and remain protected, Microsoft said through the report.
Why the disabled control matters
Smart App Control is designed to block potentially harmful applications and binaries. It combines Microsoft’s application intelligence services with Windows code-integrity capabilities and operates alongside Microsoft Defender and SmartScreen.
The update does not disable the feature on systems where it is already active. The practical risk instead falls on users and administrators who previously turned it off and now need to re-enable it but cannot do so from Windows Security.
No permanent fix was available as of October 16, 2026. Microsoft provided separate temporary procedures for individual affected devices and enterprise-managed systems.
Registry workaround for affected PCs
Microsoft’s reported workaround requires an elevated Command Prompt. Run both commands as administrator:
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
Restart the computer after adding the two registry values.
These commands create DWORD overrides under:
HKLM\SYSTEM\CurrentControlSet\Policies\Microsoft\FeatureManagement\Overrides
Group Policy option for managed environments
For enterprise-managed devices, Microsoft instructed administrators to install and configure these two policies:
Windows 11, versions 24H2, 25H2, and 26H2 – KB5074105 261015_19222 Feature PreviewWindows 11, versions 24H2, 25H2, and 26H2 – KB5074105 261015_19221 Feature Preview
Both settings should be set to Enabled, followed by a restart of the affected devices. According to the reported guidance, the policies enable Smart App Control and activate logging for troubleshooting.
The published policy names cover Windows 11 versions 24H2, 25H2, and 26H2. However, the location reproduced in the report refers only to Windows 11 versions 24H2 and 25H2, so administrators should preserve that version distinction when applying the temporary measure.
Until Microsoft releases a permanent correction, users with Smart App Control already enabled do not need to change its state. Those encountering the grayed-out control can use the registry procedure, while managed fleets can apply the two designated Group Policies.
