How to Fix Cloudflare Error 521: Web Server Is Down
Cloudflare error 521 means your origin web server is refusing the connection from Cloudflare'...
Checklists for software errors, setup, and tool workflows.
1. Reproduce
2. Isolate
3. Apply
4. Verify
Latest checklists
View listFix ERR_CERT_AUTHORITY_INVALID on Localhost
When testing a local web app, you may see ERR_CERT_AUTHORITY_INVALID in Chrome or si...
Checklist for Troubleshooting Nginx Permission Denied Errors
Understanding the Problem
When Nginx returns a 403 Forbidden or logs an error like ...
Fix Nginx Configuration Test Failure After Adding Proxy Pass
You add a proxy_pass directive to an Nginx server block, run nginx -t, ...
Chrome Extensions Not Loading: Fixes for Common Issues
If you open Chrome and notice your extensions are missing, grayed out, or not responding, you'...
Fix 'python command not found' on Windows with Python Installed
You installed Python on Windows, but when you type python --version in Command Promp...
Topic paths
Quick titles
Cloudflare 521 Error: Origin Server Unreachable FixHow to Use Git LFS Track for Large FilesResolve Python Socket Decode Errors with Encoding ChecksFix Windows Security App Not Opening After System ResetResolve Git Index Lock File ErrorGit Merge Abort Fails: How to RecoverWindows 10 Taskbar Hidden Icons Guidepnpm Cache Cleanup: When and How