Checklists for software errors, setup, and tool workflows.

1. Reproduce

2. Isolate

3. Apply

4. Verify

Latest checklists

When running npm start or npm install in a React app, you may see an er...

When Nginx returns a 502 Bad Gateway or logs upstream connection refused

Fix 'python command not found' After Windows Upgrade
After upgrading Windows 10 to 11 (or a major feature update), many users find that typing p...

Nginx Upstream Connection Refused: Diagnosis and Fixes
When Nginx returns a 502 Bad Gateway or logs "upstream connection refused", it means Ngin...

How to Enable Chrome Extensions That Aren't Loading
You open Chrome and see a grayed-out extension icon. Clicking 'Enable' does nothing, or t...

Fix 'Python' Command Not Found in Windows 10 64-bit
You open Command Prompt, type python, and see 'python' is not recogniz...