Checklists for software errors, setup, and tool workflows.

1. Reproduce

2. Isolate

3. Apply

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Latest checklists

You're in VS Code, you open the terminal, type python script.py, and get p...

How to Fix Nginx 502 Bad Gateway in Docker
If you're running Nginx as a reverse proxy inside Docker and seeing a 502 Bad Gateway error, ...

How to Set Python Path in Windows 10
If you've installed Python on Windows 10 but get 'python' is not recognized

Git Detached HEAD Warning Explained: Causes and Fixes
You see a warning: "You are in 'detached HEAD' state." This happens when you chec...

Fixing Nginx Upstream Connection Refused on Port 443
You see "upstream connection refused" in your Nginx error log when proxying requests to p...

How to Fix Cloudflare 521 Error with Firewall Settings
If you see a 521 Web Server Is Down error when visiting your site through Cloudf...