Troubleshooting a distributed application could be a major concern for most developers. Distributed logs, multiple jobs, and more than one user interface can cause sleepless nights for someone trying to troubleshoot an application. So, it becomes very important that the execution environment of your application provides enough clues about the potential cause of an error or fatal situation. Heroku application errors usually appear as error pages for the user when a web request is made. Heroku will return a standard error page with the HTTP status code 503. On top of that, Heroku adds custom error information to the application log.

The Heroku platform uses the following conventions to classify various types of these errors:

For example, the following is an excerpt from a crashed web process. The error code is indicated in a different shade.

2013-03-04T11:25:10-07:00 heroku[web.1]...