Checklists for software errors, setup, and tool workflows.

1. Reproduce

2. Isolate

3. Apply

4. Verify

Latest checklists

You have an Nginx container running on Alpine Linux, and it returns a 502 Bad Gateway. This usual...

After a Cloudflare update or configuration change, you might see SSL errors like ERR_SSL_PR...

Fix Node.js Heap Out of Memory When Loading Modules
If you see FATAL ERROR: Ineffective mark-compacts near heap limit Allocation failed - JavaS...

Fix Node Sass Build Failed GYP Error: Step-by-Step Guide
When you see "node sass build failed" with a "gyp error" during npm install, it u...

Fix DNS Probe Finished NXDOMAIN for a Specific Website
If you see the error "DNS_PROBE_FINISHED_NXDOMAIN" in Chrome when trying to visit a speci...

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