Checklists for software errors, setup, and tool workflows.

1. Reproduce

2. Isolate

3. Apply

4. Verify

Latest checklists

When Nginx returns 502 Bad Gateway or logs upstream connection refused timeout...

How to Reset Chrome to Fix ERR_NAME_NOT_RESOLVED
You try to visit a website, but Chrome shows ERR_NAME_NOT_RESOLVED. This usually...

Fix Docker 'No Space Left on Device' on Mac
You're running Docker on a Mac and suddenly get an error: no space left on device

Fix Docker Container Exits Immediately in Background Mode
You run a Docker container with -d (detached mode) and it exits immediately. The con...

Recover Lost Changes After Git Detached HEAD
You've made several edits, then checked out an old commit or tag, and now Git says you're...

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