Problems, Crashes and Errors of Heroku TODAY

This error is often caused by a process being unable to reach an external resource, such as a database, or the application doing too much work, such as parsing and evaluating numerous, large code dependencies, during startup.
The default boot timeout is 60 seconds.

"Application Error" or similar is always caused by your own application code.
Routing errors will normally only surface themselves within the logs of your application.
In most cases, you will be able to see the cause of the error there.
To learn more about logging, please see our Logging article on DevCenter.

You can view logs with the Heroku CLI, the dashboard, your logging add-on, or in your log drain.
You can't view logs for apps in Shield spaces with Private Space Logging enabled.
Retrieve logs from your log drain instead.

Heroku's HTTP router serves unstyled HTML with HTTP status code 503 (Service Unavailable) when your app encounters a system-level error, or while maintenance mode is enabled.
Other errors, such as application errors (a 404 or 500), will display your application's error page and not the Heroku error page.