Checklists for software errors, setup, and tool workflows.

1. Reproduce

2. Isolate

3. Apply

4. Verify

Latest checklists

If you see fatal: unable to access 'https://...': SSL certificate problem: unable t...

Cloudflare Wildcard Subdomain Troubleshooting Checklist
When you set up a wildcard DNS record (e.g., *.example.com) in Cloudflare, subdomain...

Nginx Redirect Loop: Common Causes and Fixes
You set up a redirect in nginx, but now your browser shows 'redirect loop' or 'too ma...

Fix VSCode Source Control Not Detecting Changes
You're working in Visual Studio Code, you edit a file, but the Source Control view shows no c...

Fix npm run build Permission Denied on Linux
You run npm run build on your Linux machine and see Permission denied. ...

Fix Nginx 'upstream connection refused' When Talking to PHP-FPM
You're seeing upstream connection refused in your Nginx error log, and your site...