This error appears when you have DoubleDown Casino open in more than one place. Each time you launch a new instance of DoubleDown Casino and log in to your player account, the newest instance becomes the only active session.
For instance, if you are playing DoubleDown Casino on your mobile device, and then you launch DoubleDown Casino on Facebook via your computer, the mobile version is automatically logged out to allow the more recent login.
If you want to play on your device again, simply close the browser tab, then tap OKAY in the app to restore the connection.
If you see this message when you are certain you have not opened the game in multiple tabs or on more than one device simultaneously, you may wish to change your Facebook password and enable Login approvals for increased account security. Please refrain from sharing your Facebook login credentials with anyone.