Fix Windows Defender Connection Refused or Permission Denied Errors
If you see "connection refused" or "permission denied" when trying to start or update Windows Def...
Software comparisons, alternatives, and tool decision notes.
Fit
Decision
Migration
Latest comparisons
Browse labFix Windows Defender High CPU Usage in Windows 10
If you notice your PC slowing down and the fan spinning up, Windows Defender might be using more ...
Fix Windows Security Cache Sync Errors: Step-by-Step Guide
If you see repeated credential prompts or Windows Security not saving settings, a cache sync issu...
Fix Windows Activation Error 0xC004F074 on a Domain
If your domain-joined Windows machine shows activation error 0xC004F074, it usually means the sys...
Fix Windows Defender 404 Not Found After Update
After installing a recent Windows update, some users find that Windows Defender is missing or sho...
Fix 'Windows Defender File Locked by Another Program' Error
You try to delete, move, or rename a file, and Windows shows an error: “The action can’t be compl...