Microsoft has fixed a Windows issue that repeatedly warned some users that Microsoft Defender Antivirus was turned off, even when the antivirus was active and functioning correctly.
The fix is included in Microsoft Defender Antivirus version 4.18.26080.4, released on September 17. Microsoft lists the issue as resolved in its Windows release health documentation.
What the false warning looked like
Affected PCs could show a Windows Security notification asking users to turn on Microsoft Defender Antivirus. The alert could appear when Windows started and return later, even after notification settings were disabled.
Microsoft says Defender remained functional and its settings showed the antivirus as active. The issue covered supported Windows client and server versions running the latest Defender updates, including Windows 10, Windows 11, and Windows Server editions.
BleepingComputer’s report notes that the problem had been seen in Windows Insider testing before Microsoft acknowledged it publicly in late August. The problem was a reporting error, so the notification itself did not prove that malware had disabled Defender.
How to check your PC
Defender updates normally arrive through Microsoft’s update channels. If you saw the warning, open Windows Security and check that Virus & threat protection reports active protection and a recent threat scan.
You can also check the main Defender status values in PowerShell:
Get-MpComputerStatus | Select-Object AntivirusEnabled,RealTimeProtectionEnabled,AMServiceEnabledThe three values should show True on a PC where Defender Antivirus is enabled and running. Microsoft also publishes current Defender platform information on its security intelligence updates page.
Users who still see the warning should first install the latest Defender updates and then check Windows Security again. Microsoft has marked the underlying notification issue as resolved.
Sooraj Raj is a programmer, blogger and professional developer with an interest in technology research and publishing. He writes about technology developments and shares information in a clear, straightforward way.
