Knowledge base for software setup, errors, and daily tool work.

Fix ERR_NAME_NOT_RESOLVED in Chrome: Proxy Settings Guide

If you see ERR_NAME_NOT_RESOLVED in Chrome, it usually means the browser can'...

Nginx Upstream Connection Refused: Diagnosis and Fixes

When Nginx returns a 502 Bad Gateway or logs "upstream connection refused", it means Ngin...

Fixing Nginx Upstream Connection Refused on Port 443

You see "upstream connection refused" in your Nginx error log when proxying requests to p...

Cloudflare 522 Error: Server Response Time Troubleshooting

You're browsing a site and get a Cloudflare 522 error—'Connection timed out' or '...

Checklist for Troubleshooting Nginx Permission Denied Errors

Understanding the Problem

When Nginx returns a 403 Forbidden or logs an error like ...