Defender Antivirus "turned off" 25H2 26200.9168

Microsoft Defender shows as disabled even though it is active – Windows 11 25H2

Hello everyone,

For some time now, I have been receiving a notification upon Windows startup stating that my antivirus protection is disabled.

Under Windows Security → Security providers, it displays:

Microsoft Defender Antivirus is disabled.

At the same time, the main Windows Security page shows all areas as green. Defender also appears to be fully functional.

System:

• Windows 11 25H2
• Build 26200.9168
• Microsoft Defender, no other virus scanner

I have performed the following checks:

Get-MpComputerStatus returns:

• AntivirusEnabled: True
• RealTimeProtectionEnabled: True
• AMServiceEnabled: True
• AntispywareEnabled: True

The Microsoft Defender Antivirus Service (WinDefend) is also running.

Get-CimInstance -Namespace root/SecurityCenter2 -ClassName AntivirusProduct lists Windows Defender as the registered antivirus product.

Update-MpSignature also works without issues. The following versions are currently displayed:

• AntivirusSignatureVersion: 1.457.298.0
• AMProductVersion: 4.18.26070.9
• AMEngineVersion: 1.1.26070.7

So, Defender appears to be active and functioning correctly. It is only Windows Security (or the Security Center) that reports it as disabled and triggers a corresponding warning at system startup.

Is this issue with Build 26200.9168 known, and is there already a solution or workaround for it?