Checklists for software errors, setup, and tool workflows.

1. Reproduce

2. Isolate

3. Apply

4. Verify

Latest checklists

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

Fix npm 'package.json not found' Error in Subdirectories
You're working in a subdirectory of your project, run npm install or npm r...

Fix Nginx Upstream Connection Refused Error
When Nginx returns upstream connection refused in your error logs, it means Nginx tr...

Node.js Heap Out of Memory in Production: Practical Fixes
You're running a Node.js application in production when it crashes with FATAL ERROR: In...

Fix DNS Probe Finished NXDOMAIN: Chrome Flags Reset Guide
When you see DNS_PROBE_FINISHED_NXDOMAIN in Chrome, it usually means the browser...

Git Detached HEAD: Practical Checklist and Fixes
You see a message like 'You are in 'detached HEAD' state' when checking out a com...