Fix Windows Defender Service Not Starting (Error 404)
If you see error 404 when trying to start Windows Defender, it usually means the service executab...
Checklists for software errors, setup, and tool workflows.
1. Reproduce
2. Isolate
3. Apply
4. Verify
Latest checklists
View listHow to Fix Windows Search 'Permission Denied' Error
When you search for a file or setting in Windows and get a 'Permission Denied' error, it usually ...
Fix 'PowerShell Execution Policy Change Permission Denied' Error
When you try to change the PowerShell execution policy and get a 'permission denied' error, it us...
Fix Windows Activation License Expired After Upgrade
After a major Windows upgrade (e.g., from Windows 10 to Windows 11 or a feature update), you may ...
Fix Windows Backup Error 0x81000019 on System Restore
When you try to restore a Windows backup, error 0x81000019 can stop the process. You might see th...
Checklist for Fixing Windows Security Startup Failure
When Windows Security (formerly Windows Defender) fails to start at boot, you may see an error li...
Topic paths
Quick titles
Essential Windows Terminal Tweaks for New InstallationsPostgreSQL Connection Refused Firewall FixFix Windows Search Connection Refused on Windows 10/11Troubleshoot Windows Terminal Font IssuesFree Disk Space by Cleaning Task Scheduler LogsRemote Desktop Timeout Due to Firewall: Step-by-Step FixStuck in BitLocker Recovery After Windows 11 UpdateRemote Desktop Error 0x4 Troubleshooting Guide