**Microsoft** has confirmed that its latest **Windows 11** security update, **KB5127648**, is causing an unexpected issue: some users are finding the **Smart App Control** option grayed out and inoperable within the **Windows Security** app. **Smart App Control** is a robust security feature in **Windows 11** designed to block potentially harmful applications and binaries. It leverages **Microsoft**'s app intelligence services and code integrity features, working in conjunction with **Microsoft Defender** and **SmartScreen** to enhance system protection. The bug specifically impacts devices running **Windows 11, version 24H2** and later, where the feature was previously turned off. "After installing this update, some devices might be unable to turn on **Smart App Control** in the **Windows Security** app if it has been turned off. On affected devices, the option to turn on **Smart App Control** might be grayed out," **Microsoft** stated in an update to the **KB5127648** advisory. Crucially, devices where **Smart App Control** is already enabled are not affected and continue to benefit from its protection. ### Temporary Workarounds Provided While a permanent fix is still in development, **Microsoft** has provided temporary workarounds for IT administrators to mitigate the issue, particularly on enterprise-managed devices. These involve modifying the system registry or implementing Group Policies. To restore the ability to enable **Smart App Control** via the registry, administrators can follow these steps: 1. Open **Command Prompt** as an administrator. 2. Execute the following commands: 3. Restart the device. Alternatively, IT admins can utilize Group Policies. **Microsoft** has released two specific Group Policy packages, **KB5074105 261015_19222 Feature Preview** and **KB5074105 261015_19221 Feature Preview**, for **Windows 11, versions 24H2, 25H2, and 26H2**. These can be found under `Computer Configuration > Administrative Templates > {Group Policy name} > Windows 11, version 24H2, 25H2`. After installation, both settings must be set to **Enabled**, and the device(s) restarted for the policies to take effect. ### Other Recent Windows Update Issues This incident is one of several recent issues tied to **Windows** updates. **Microsoft** recently acknowledged that other **Windows** updates were causing **Remote Desktop** failures for non-admin users when the "Administrator protection" feature was enabled. The company also addressed problems with **Always On VPN** connections following the September 2026 security updates. Furthermore, a bug that led to black screens, desktop loading issues, and Explorer crashes after installing **Windows 11** updates since August has also been resolved.