Hi everyone. I want to remind everyone that this error message sounds more scary than it actually is.
For most people, you will see this message if you type in your account name incorrectly. So instead of getting an error that says "You typed your name wrong" you get "Error #004". We'll try and patch this soon so that it's more intuitive.
I'm fairly sure that most other people that get this message I strongly suggest logging into the Aeria Games website with your account, wait a few minutes, and then try logging into the game again.
If this doesn't work, please contact our support team:
http://www.aeriagames.com/contact
-Ando