Windows Security Troubleshooting Guide
Windows Security (formerly Windows Defender) usually runs quietly in the background, but sometime...
Checklists for software errors, setup, and tool workflows.
1. Reproduce
2. Isolate
3. Apply
4. Verify
Latest checklists
View listFix Windows Defender Not Opening Error 404
You try to open Windows Defender and get an error 404 – the page or resource can't be found. This...
How to Fix Windows Defender 502 Bad Gateway Error
If you see a '502 bad gateway' error in Windows Defender, it usually means the security service c...
Fix Windows Search Error 0x80004005 (Crashes)
If Windows Search keeps crashing and shows error 0x80004005, search results stop appearing or the...
How to Fix Task Scheduler Permission Denied Error
When you try to create or run a task in Windows Task Scheduler and get a "Permission denied" erro...
Fix 'Permission Denied' and 'Windows Update Module Not Found' Errors
You try to run Windows Update, but you get a "permission denied" error or a message that the upda...
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