You are using an old oTree version Your otree package is out-of-date (version 2.2.4; latest is 5.9.2). You should upgrade with: "pip3 install --U otree" and update your requirements_base.txt.
You are using a proper database (Postgres, MySQL, etc).
DEBUG mode is off
You are using a server other than runserver.
No password protection To prevent unauthorized server access, you should set the environment variable OTREE_AUTH_LEVEL.
Your database appears to be synced.
The worker process is running