Microsoft fixes bug that blocked Smart App Control on some Windows 11 PCs
Affected machines can turn the security feature back on once they install updates released on or after October 28, 2026.
Microsoft has fixed a bug introduced by the October 2026 KB5127648 update that left some Windows 11 devices unable to re-enable Smart App Control, with the toggle greyed out on affected 24H2-and-later machines. The company confirmed the fix is included in updates released on or after October 28, 2026, starting with the November preview update KB5127936. Administrators who want to avoid the preview update can apply a temporary registry change and restart the device, or deploy specific feature preview Group Policies that enable the feature and turn on troubleshooting logs. Devices where Smart App Control was already active were never affected.
Why it matters
The bug left some Windows 11 users unable to re-enable Smart App Control after the October update, which meant the protection could not be restored on those machines. Devices that already had it running were not affected, so the change matters most to people who had switched it off or been unable to turn it back on. With the fix now shipping in later updates, the setting can be restored through normal patching, and administrators who need it sooner have a documented registry workaround.
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