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 Security 404 Error When Opening
When you open Windows Security and see a 404 error page, it usually means the app can't find its ...
Fix Chrome Offline Installer Error 0x80070002
When downloading the Chrome offline installer, error 0x80070002 usually means the installer file ...
How to Fix Windows Activation Port Already Allocated Error
When activating Windows, you may see an error message like "The activation port is already alloca...
Fix Windows Security Network Error: Not Connecting
If you see “Windows Security network error not connecting” when trying to access network resource...
Fix Windows Defender Invalid Configuration After Update
After a Windows update, you might open Windows Security and see a yellow warning: "Invalid config...
Topic paths
Quick titles
Fix Windows Update 502 Bad Gateway Due to DNS ConfigurationWindows Defender Version Sync Error FixHow to Resolve ERR_TUNNEL_CONNECTION_FAILED Mac ChromeWindows Update 0x800f081f: SFC and DISM Repair GuideReduce Outlook Memory Usage: IT Admin GuideFix Windows Defender Update Error 0x80240022Resolve Defender Version Mismatch on Windows 10Fix Stale Windows Security Token