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Microsoft 365 and Office | Microsoft 365 Defender | For home | Windows
An integrated threat protection solution designed to detect, investigate, and respond to cyber threats across Microsoft 365 services.
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Thanks for posting in the Microsoft Community, I understand how you feel this must be to run into the Could not sign in to Microsoft Defender error when you're trying to access your security settings. Since the standalone Microsoft Defender app requires a personal Microsoft account with an active Microsoft 365 subscription, could you please confirm if you are using one? Also, let me know what troubleshooting steps you have already tried such as turning off a VPN, syncing your date and time, or resetting the app so I don't ask you to repeat anything and we can get this fixed quickly.