That “undocumented” error comes from our proxy, and indicates that it can’t connect to your app.
Try running fly vm status e1ed0979 and see what it says. My guess is that health checks are failing. Possibly because your app isn’t listening on 0.0.0.0 or it’s expecting the wrong port.
What is your fly.toml file? See if the internal_port in there is set to 5000. That needs to match what Rails is listening on.