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 listNginx Redirect Loop: Common Causes and Fixes
You set up a redirect in nginx, but now your browser shows 'redirect loop' or 'too ma...
Fix Nginx Upstream Connection Refused Timeout Error
When Nginx returns 502 Bad Gateway or logs upstream connection refused timeout...
Cloudflare DNS Not Updating After Change: Fixes That Work
You change a DNS record in Cloudflare, wait, and the old IP still resolves. This is a common frus...
Fix Cloudflare Wildcard Subdomain SSL Not Working
You set up a wildcard SSL certificate for your domain on Cloudflare, but some subdomains still sh...
Git Clone Connection Timed Out: Troubleshooting Checklist
When you run git clone and get a connection timed out error, the cl...
Topic paths
Quick titles
Resolve Nginx Redirect Loop Behind CloudflareTroubleshooting RDP Connectivity ProblemsFix Docker Context Canceled Error on MacFix Python pip Permission Denied ErrorTroubleshoot Unbound Breakpoints in Remote VS CodeFix DNS Probe Finished NXDOMAIN in Edge BrowserFix 'python command not found' on Windows with Python InstalledWindows 11 Assistant Stuck at 99% Fixes