我试图了解Heroku的部署。当我尝试使用mongoDb部署在Nodejs中构建的测试应用程序时，它报告了以下三行崩溃的消息。我不太了解到底是什么导致了此错误。感谢帮助！
2019-10-11T16：59：25.802308 + 00：00 heroku [router]：at =错误代码= H10 desc =“应用程序崩溃”方法= GET路径=“ /”主机= fitnessworkoutapp.herokuapp.com request_id = 11cb4fff-97e4-41d1-aa55-8b5790fe0384 fwd =“ 84.238.97.184” dyno = connect = se84.238.97.184“ dyno = connect = service = status = 503 bytes = protocol = https
2019-10-11T17：01：41.121424 + 00：00 heroku [router]：at =错误代码= H10 desc =“应用程序崩溃”，方法= GET path =“ /” host = fitnessworkoutapp.herokuapp.com request_id = 56afd79e-a559-4da6-ada9-1dafec80b3c6 fwd =“ 84.238.97.184” dyno = connect = se84.238.97.184“ dyno = connect = service = status = 503 bytes = protocol = https
2019-10-11T17：04：02.387025 + 00：00 heroku [router]：at =错误代码= H10 desc =“应用程序崩溃”方法= GET path =“ /” host = fitnessworkoutapp.herokuapp.com request_id = 25097e7e-6349-4bb7-85a9-89408405a5ee fwd =“ 84.238.97.184” dyno = connect = se84.238.97.184“ dyno = connect = service = status = 503 bytes = protocol = https