
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 Windows Security and see the message: "Windows Security failed to start. Corrupted syste...

If Command Prompt opens and then immediately closes, or crashes randomly while you're using it, y...

If you notice PowerShell taking several seconds to start or import modules, the delay often comes...

You may see a Windows Defender error like 'Token expired' or 'The token is expired' in the Window...

If you see Outlook for Mac error 17199, it usually means the app can't connect to your email serv...