The "Application failed to respond" error means our proxy cannot communicate with your app, typically because it is not listening on the correct host and port. Your app needs to bind to host 0.0.0.0 and use the PORT environment variable that we inject automatically. Our troubleshooting guide covers this in detail with examples for common frameworks.

check your deploy logs first, go to your railway dashboard, click your service, then deployments, then click the latest deploy the logs will tell you exactly what went wrong. without seeing those i'm just guessing. paste them here and i can help you fix it