Checklists for software errors, setup, and tool workflows.

1. Reproduce

2. Isolate

3. Apply

4. Verify

Latest checklists

If you notice your PC slowing down and Task Manager shows Windows Security (or Antimalware Servic...

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

You open Outlook and see an error like "Outlook module not found" or "Configuration module not fo...

You click Windows Security in the Start menu or try to open Virus & threat protection, and instea...

When you open Windows Security (formerly Windows Defender Security Center) and see a 504 ...

How to Find the Windows Activation Log File
If you're having trouble activating Windows or just want to verify your licensing status, the act...