Oh God

Whoever is working on this website and created the application layer error. I offer the following advice

Maybe you are running production mode without setting a secret key. If not, refer to your server console for more details. Sometimes it is due to the secret key not being set for production mode.

run command "rake secret" in the terminal. Then you will see secret key

Check your application directory logs, you might see something like

//Rack app error: #<RuntimeError: Missing secret_token and secret_key_base for 'production' environment, set these values in config/secrets.yml>

Please don't let this happen again