Microsoft Defender Bug Triggers False “Virus Protection Is Off” Alerts

Microsoft has confirmed a Microsoft Defender Antivirus defect that falsely warns Windows users that virus protection is turned off even when Defender and real-time protection remain enabled and functioning. The recurring “Turn on virus protection” notifications can appear at startup or intermittently afterward, including after they are dismissed, and may bypass Windows notification controls and Do Not Disturb settings.

The issue affects supported Windows client and server releases, with reports spanning Windows 10 and Windows 11 versions through 26H1, as well as Windows Server 2025. Microsoft advises users to ignore the erroneous alerts while it develops a correction to be distributed in a future Defender Antivirus update; organizations should nevertheless verify Defender’s actual protection status, as genuine security warnings and social-engineering imitations remain possible.