Application error in heroku

State changed from crashed to starting
2020-05-17T08:04:09.019095+00:00 app[web.1]: Iris listening on port 8000
2020-05-17T08:04:09.195805+00:00 app[web.1]: Mongoose connected
2020-05-17T08:04:39.389757+00:00 heroku[router]: at=error code=H20 desc=“App boot timeout” method=GET path="/" host=app-api222.herokuapp.com request_id=4a2d314b-eea7-4b44-861c-f74c051b9ab1 fwd=“183.87.52.166” dyno= connect= service= status=503 bytes= protocol=https