Why am I seeing "Application Error"?

Resolution

"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.

To track this kind of issue down you should look at your logs:

$ heroku logs --tail --app your_app_name

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.

If you can't see the source of the error straight away, try restarting your app from another terminal window or via the Heroku Dashboard:

$ heroku restart

There are some errors which only occur when the app is rebooting so you will need to restart the app to see these log messages appear.

For most apps, we also recommend enabling one of the free logging addons from https://elements.heroku.com/addons#logging to make sure that your historical log data is being saved. Many of these have searchable web interfaces which can be helpful in tracking issues over time.

If you find an error message that you don't understand, try checking out the following resources: