Windows 10 and 11 users are seeing a Defender warning that isn’t real

Over the past few days, some Windows 11 users have been getting incorrect warning messages about Microsoft Defender—the operating system’s built-in security solution—being disabled.

According to Microsoft in this Windows Health post, the warnings are caused by a bug that was introduced in the latest Defender updates:

After installing the latest updates for Microsoft Defender Antivirus, notifications might appear stating that “Microsoft Defender Antivirus is turned off,” even though the antivirus is functioning correctly and all settings show it as active. These notifications can appear when Windows starts and intermittently afterward. They persist even if notification settings are turned off.

Per Microsoft, this bug currently affects Windows 10 (versions 22H2, 21H2, Enterprise LTSC 2019, Enterprise LTSC 2016), Windows 11 (versions 26H1, 25H2, 24H2, and 23H2), and Windows Server (versions 2025, 2022, 2019, 2016, 2012 R2, and 2012). The bug is scheduled to be fixed in the next Defender update, which currently has no release date:

Next steps: We are working to release a resolution in a future Microsoft Defender Antivirus update and will provide more information when it is available.

Further reading: 5 Microsoft Defender settings I always change ASAP