Microsoft has fixed a Windows 11 issue that prevented some users from enabling Smart App Control after installing the October 2026 security update, KB5127648. The problem affected devices running Windows 11 24H2 or later when Smart App Control was already disabled, while systems with the feature enabled continued to receive protection.
Smart App Control uses Microsoft’s code integrity features and app intelligence services, together with SmartScreen and Microsoft Defender, to block potentially malicious applications and binaries.
Smart App Control activation issue resolved
On affected devices, the Smart App Control setting in the Windows Security app appeared grayed out and could not be enabled.
Microsoft described the issue in its KB5127648 advisory:
“After you install this update, some devices may be unable to turn on Smart App Control if it is turned off in the Windows Security app. The option to turn on Smart App Control may be grayed out on affected devices. Devices that already have Smart App Control turned on are not affected and will continue to be protected.”
Microsoft confirmed Wednesday that the issue was resolved in the Windows update released on October 28, 2026. The fix was included in the KB5127936 preview update.
In service alerts sent to IT administrators, Microsoft said: “This issue was resolved in a Windows update released on October 28, 2026. [..] And after that. We recommend that you install the latest security updates for your device, as this update contains important improvements and resolutions to issues.”
Workarounds for affected devices
Administrators who do not want to deploy the preview update to enterprise-managed devices can use a temporary registry workaround while waiting for the next monthly Patch Tuesday cumulative update.
To apply the workaround, open an elevated Command Prompt by searching for cmd, selecting Run as administrator, and running the following commands:
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 /fAdministrators can also use a Group Policy workaround to enable Smart App Control and logging for troubleshooting. A restart is required on affected devices for the Group Policy settings to take effect.
Other fixes in the KB5127936 preview update
The KB5127936 preview update also addresses remote desktop failures triggered by recent Windows updates when the Administrator Protection security feature is enabled.
It additionally fixes Always On VPN problems caused by the September 2026 cumulative update.
Source: www.bleepingcomputer.com