Microsoft Fixes Windows Bug That Falsely Warned Defender Was Disabled

Microsoft has fixed a Windows issue that incorrectly warned users that Microsoft Defender Antivirus was turned off even though antivirus protection remained active.

The problem was resolved with Microsoft Defender Antivirus version 4.18.26080.4, released on September 17. Microsoft acknowledged the issue in late August, although Windows Insider users had reported similar warnings since at least June.

The bug affected all supported Windows versions

Microsoft says the issue affected all supported Windows client and server versions, including Windows 11 26H1 and Windows Server 2025.

Affected systems could show a Windows Security notification stating “Microsoft Defender Antivirus is turned off” and prompt users to enable protection.

However, Defender continued working correctly, and its settings still showed Microsoft Defender Antivirus as active. The false notifications could appear when Windows started and then return intermittently.

Microsoft also said the alerts could continue appearing even when users disabled Windows notifications, making it difficult to suppress the warnings without addressing the underlying Defender issue.

Users should install the latest Defender update

Microsoft has resolved the incorrect alerts in Microsoft Defender Antivirus version 4.18.26080.4.

Users who encountered the issue should make sure Microsoft Defender Antivirus has updated to version 4.18.26080.4 or later.

In other news, Microsoft is cutting off Windows 11 24H2 Home and Pro updates next month, while Microsoft Graph PowerShell v3 will drop Windows PowerShell 5.x support.

Via BleepingComputer