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 Cloudflare Origin Certificate Not Trusted by Browser
You've set up Cloudflare with an origin certificate, but browsers show a warning that the cer...
Fix Chrome Status Access Violation After Update
After a Chrome update, some users see a status access violation error when openi...
How to Stop Nginx Redirect Loop: Practical Fixes
An Nginx redirect loop (too many redirects) usually appears as a browser error after multiple 301...
Fix Nginx 'Permission Denied' Upstream Errors
When Nginx logs permission denied while connecting to an upstream (e.g., a Unix sock...
Fix Windows 11 WiFi No Internet Due to Proxy Settings
If your Windows 11 laptop shows full WiFi bars but browsers say “No internet,” a common culprit i...
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