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

Chrome Sync Stuck on Waiting for Sync: Practical Fixes
You open Chrome, click the profile icon, and see the never-ending 'Waiting for sync' mess...

Fix VS Code Git Authentication Failed Keychain Error
If you see "Git authentication failed" in VS Code on macOS, the problem is often the macO...

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...

Fix Cloudflare 521 Error Due to Server Overload
You see a Cloudflare 521 error page. The message says the web server is down. Often, this means y...

Fix Nginx Configuration Test Failure on Location Directive
When you run nginx -t and see an error like [emerg] invalid location directive...