2020?05?17T14:43:36.398942+00:00 heroku[router]: at=error code=H10 desc=?App crashed? method=GET path=?/? host=rainroom.herokuapp.com request_id=cd25b8f8-e509?455a-a019-e8f940e73593 fwd=?000.000.000.000″ dyno= connect= service= status=503 bytes= protocol=https2020?05?17T14:43:37.124714+00:00 heroku[router]: at=error code=H10 desc=?App crashed? method=GET path=?/favicon.ico? host=rainroom.herokuapp.com request_id=52309f75-ac3a-4d8c-9b7b-c5ab83f310a9 fwd=?000.000.000.000″ dyno= connect= service= status=503 bytes= protocol=https2020?05?17T14:43:48.068633+00:00 heroku[router]: at=error code=H10 desc=?App crashed? method=GET path=?/? host=rainroom.herokuapp.com request_id=61540db6?51c4?4cd5-a37a-713633c0baa9 fwd=?000.000.000.000″ dyno= connect= service= status=503 bytes= protocol=https
This problem occurred by your wrong port setting by manually
From this.
Change to this.
Because Heroku has to use their own port by themselves. but You can use your port when you are developing.