Windows 11’s October update blocks Smart App Control. Here’s the fix

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.