Checklists for software errors, setup, and tool workflows.

How to Fix Cloudflare 521 Error (Port 443 Blocked)

When you see a Cloudflare 521 error, it means Cloudflare’s servers cannot connect to your origin ...

Fix Nginx 502 Bad Gateway with Docker and PHP-FPM

You have a Docker setup with Nginx proxying to a PHP-FPM container, and you're getting a 502 ...

Fix Windows Cannot Access Shared Folder: Advanced Sharing Settings

You try to open a shared folder from another PC on your network, but Windows shows an error: "...

Docker Container Exits Immediately: How to Find Logs and Fix It

You start a Docker container and it stops within seconds. The status shows "Exited (0)" o...

Fix 'package.json Not Found' After Cloning a Repository

Symptom

You clone a repository from GitHub (or another remote), change into the directory...

Windows Update Service Troubleshooting Checklist

When Windows Update stops working, the update service itself is often the culprit. You may see er...