If you are unable to start the app, please try restarting your device. If you are still unable to start the application, please contact support by filing a ticket here, with a step-by-step breakdown of what you did to see the error.
If you are able to start the app, and an error occurs consistently, please file a ticket from within the game by going to Settings > Support and sending us an email. The email will automatically contain your support token which will assist us in debugging your issue.
In general, please be sure to include your support token in all requests, as we are unable to help without it.