Checklists for software errors, setup, and tool workflows.

1. Reproduce

2. Isolate

3. Apply

4. Verify

Latest checklists

You try to run a Python script in VSCode, click the terminal tab, and nothing happens—or the term...

Cloudflare error 521 means your origin web server is refusing the connection from Cloudflare'...

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

Fix 'npm package json not found' Error When Using npx
When you run npx some-package and see an error like “npm package json not found”...

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

Nginx Permission Denied After Restart: Fixes That Work
After restarting nginx, you might see errors like connect() to unix:/var/run/php-fpm.sock f...