Some users are getting an “Unable to log into Microsoft Defender” error on Windows 11 after the August 2023 cumulative update, which resolved SSD issues. Not to be confused with the Windows Security app, Microsoft Defender is a new app that acts as a security dashboard for all connected devices.
The error is likely linked to the two updates released on August 8 – the Microsoft Defender update and Windows 11 KB5029263, the security update causing issues. I have received multiple reports from our readers, including a screenshot showing the login error message when launching Defender.
Unable to log into Microsoft Defender error caused by August 2023 security updates
Users have also highlighted the problem on Feedback Hub, with most Windows 11 users blaming the August 2023 Patch Tuesday and some claiming the issue is caused by the Defender update.
“After installing (KB5029263), MS Defender asked for a login. I provided my Live ID credentials, and it said it couldn’t log me in with the message “Unable to log into Microsoft Defender”. That’s a problem”,” a frustrated user…