Microsoft has resolved a software defect in Windows Security that triggered incorrect notifications regarding the status of Microsoft Defender Antivirus. The issue caused the system to falsely report that the antivirus protection was disabled, even when it was fully operational.
The fix is included in the Defender platform update version 4.18.26080.4, which was released on September 17. The update installs automatically on all supported versions of Windows and Windows Server, provided that users have not restricted mandatory security updates via Group Policy or the Registry Editor.
The company officially acknowledged the bug on August 28. Users in the Windows Insider program had reported encountering these warnings since June. The false alerts typically appeared during system startup or at random intervals, redirecting users to the Windows Security dashboard where the service appeared active.
