Checklists for software errors, setup, and tool workflows.

Fix Nginx 502 Bad Gateway on Docker Ubuntu

You're running Nginx as a reverse proxy inside Docker on Ubuntu, and suddenly you see

How to Fix Cloudflare Error 521: Server Not Responding

Cloudflare error 521 appears when your origin server refuses the connection from Cloudflare's...

Python Virtual Environment Not Activating in Git Bash: Fixes

You're in Git Bash on Windows, you run source venv/Scripts/activate, and nothing...

Fix Nginx Permission Denied for Static Files

Common Causes

When Nginx returns a 403 Forbidden or 'permission denied' error for...

Fix Chrome Certificate Error Invalid Authority on Mac

You're browsing in Chrome on a Mac and suddenly see a warning: Your connection is not...