DEBUGmode, you will no longer see Django’s yellow error pages; you or your users will just see generic "500 server error" pages. oTree offers a free Sentry service; you can find the sign-up link in the oTree documentation.
The worker process enables the following functionality:
timeout_seconds), then the timeoutworker will automatically advance a user when they exceed the timeout, even if they close their browser.
In your app dashboard, make sure the second dyno is turned on.