Heroku Error H10 (App crashed)

According to their Developer documentation:

Check your app’s backtrace in the logs to find out what you need to do to fix the problem.

https://devcenter.heroku.com/articles/errors

I had a similar problem, every time I hit the server, I just got these 2 useless lines of output in the logs.

When I ran:

heroku restart

It ended up showing me more output that let me track down my issue (related to migrating to cedar) (the app was crashing on deploy it appears, never fully starting up, but not showing an error during the deploying process, as would usually occur).