Cloudflare Error 521: Web Server Down Checklist
Cloudflare error 521 means your origin web server refused the connection. This is not a Cloudflar...
Checklists for software errors, setup, and tool workflows.
1. Reproduce
2. Isolate
3. Apply
4. Verify
Latest checklists
View listFix Nginx Upstream Connection Refused Socket Error
When Nginx returns a 502 Bad Gateway or logs upstream connection refused
Fix pnpm Permission Denied Errors on macOS
When running pnpm on macOS, you may encounter a EACCES: permission denied error, esp...
Fix Node Sass Build Failed: Reinstall Steps
If you're seeing a "node sass build failed" error when running npm install or buildin...
Fix Missing Taskbar Icons on a Second Monitor
If you've connected a second monitor and the taskbar icons aren't showing up on it, you&#...
Fixing Python Requests Connection Timeout Errors
When your Python script using the requests library hangs or raises a ConnectTi...
Topic paths
Quick titles
Troubleshoot Windows Update Service for System RestoreHow to Fix Python Not Found in Windows PowerShellChrome Update Broke Sync: Troubleshooting StepsERR_NAME_NOT_RESOLVED Fix Using Command PromptHow to Stop Explorer Crashing in Safe ModeWindows 11 Blue Screen After Update: How to FixFix Cloudflare Origin Certificate with Let's EncryptHow to Fix Windows Cannot Access Shared Folder in Windows 10