In this chapter, we reviewed various ways of troubleshooting Heroku applications. We looked at how logging works in Heroku and how to leverage the Heroku CLI utility to review application logs and troubleshoot specific problems. We also reviewed the available techniques to troubleshoot app downtime, debug HTTP requests, and process the formation of your app. We also found how you could roll back your app to a prior working condition when every other troubleshooting technique fails. We discovered a recommended app configuration that helps the app avoid errors and downtime. We learned how to handle maintenance windows and avoid timeouts. Finally, we delved deep into Heroku's error code system—the error-naming convention and the error code catalog of Heroku.

In the next chapter, we will learn the advanced features of the Heroku platform and how to leverage those features to build and deploy feature rich, performant, scalable, and production-ready web apps.