After installing update KB5127648, which was released on October 13th for Windows 11 versions 24H2, 25H2, and 26H2, fixes certain bugs like mouse glitches while gaming and black screens after logging on, but it also introduces another problem involving the “Smart App Control” feature.
Smart App Control is a Windows security feature designed to prevent potentially harmful programs from running on your computer. It works by screening applications through Microsoft’s cloud service to detect and isolate infected, compromised, or otherwise dangerous executables.
However, after installing the October 2026 update, the option to activate Smart App Control is suddenly grayed out for some users.
According to Microsoft, only PCs on which Smart App Control was already disabled are affected. Users who already had the feature enabled remain protected by the feature—it’s not automatically disabled, but it also cannot be re-enabled if you end up disabling it.
Microsoft has released a temporary workaround that involves modifying two values in the Windows Registry. The company recommends creating a backup of the registry before making any changes. A separate solution is also available for enterprise computers via Group Policy.
The two Windows registry tweak commands are as follows:
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 /fFurther instructions can be found on the update’s release notes, located under the “Known issues in this update” section with the label “You might be unable to turn on Smart App Control.”
Microsoft is working on a permanent fix but has not yet announced when it will be available. As long as Smart App Control is disabled, an important automatic layer of protection against unknown or potentially harmful apps is missing. This means malicious apps can slip through, even if normal Defender protection is in place.
Further reading: Is Windows 11’s built-in antivirus security enough for normal users?