Error 100 is a Desynchronization of your session with the Server and it should only be temporary. If it persists more than a few minutes, it might be worth restarting the app or even your device.
If this does not help either, you can try uninstalling the game and reinstalling the application. Once you arrange this, if you lose access to your old progress, please get in touch with us as we can help you to recover it.
If the error still persists, please contact Customer Support by submitting a ticket here.