Hey there,

"Connection lost" issue with n8n in Codespaces , It usually happens because the Codespace environment doesn't forward the WebSocket connection correctly by default, or n8n doesn't know its own public URL.

Here is the fix that worked for me:

1. Fix the "Connection Lost" UI Error The browser is losing contact with the n8n backend.

Go to the Ports tab in your Codespace (bottom panel near the terminal).

Find port 5678 (or whichever port n8n is running on).

Right-click it and change Port Visibility to Public.

Why? If it's set to "Private," the authentication cookies sometimes interfere with the WebSocket connection n8n uses to update the UI.

2. Configuring the Monitor (HTTP Request Node) Since your HTML app is running in the same Codespace as n8n, you shouldn't use the public https://...app.github.dev URL in your HTTP Request node.

The Problem: If you use the public URL, the request goes out to the internet and hits the GitHub Codespace authentication wall (which returns a 403 or Login page), causing the node to fail.

The Fix: Use the local Docker network address. In your HTTP Request node, set the URL to: http://localhost: (e.g., http://localhost:3000) or http://127.0.0.1:

This keeps the traffic internal and bypasses the public auth checks.

Hope this gets your workflow running!