Checklists for software errors, setup, and tool workflows.

1. Reproduce

2. Isolate

3. Apply

4. Verify

Latest checklists

If you're seeing FATAL ERROR: Ineffective mark-compacts near heap limit Allocation fail...

How to Fix Nginx Upstream Connection Refused Error
If you're seeing upstream connection refused in your Nginx error logs, it usuall...

How to Fix Docker Pull 'Access Denied' or 'Permission Denied'
When you run docker pull and see access denied or permission deni...

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 Nginx Configuration Test Failure After SSL Setup
You've just added SSL certificates to your Nginx server block, but nginx -t retu...

How to Manually Remove a Stuck Git index.lock File
If Git operations suddenly fail with an error like fatal: Unable to create 'path/.git/i...