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 Fix Cloudflare 521 Error with Firewall Settings
If you see a 521 Web Server Is Down error when visiting your site through Cloudf...

Fix ERR_CONNECTION_RESET Caused by Chrome Extensions
If Chrome suddenly shows ERR_CONNECTION_RESET on sites that used to work, a misb...

How to Fix Git index.lock File Exists Error on Mac
If you're working with Git on a Mac and see the error fatal: Unable to create '/pat...

How to Fix Git Push Rejected Non-Fast-Forward Error
You run git push and get ! [rejected] with non-fast-forward

Setup Cloudflare Origin Certificate for Nginx
If you use Cloudflare as a reverse proxy, enabling HTTPS between Cloudflare and your Nginx server...