
Windows Defender Service Troubleshooting Checklist
If Windows Defender won't start, won't update, or shows error messages like "Service stopped" or ...

If Windows Defender won't start, won't update, or shows error messages like "Service stopped" or ...

You open Outlook and see: "Cannot start Microsoft Outlook. Cannot open the Outlook window."

You click 'Check for updates' and see the progress bar stuck at 0% or a percentage that doesn't m...

You launch Windows Terminal and see nothing but a blank window—no cursor, no prompt, just an empt...

You open Remote Desktop, enter the computer name, and get either "Connection refused"

You join a Teams meeting and your video is black, or you get an error that the camera can't be fo...