I have searched for the information about this error but had no success. Based on your error, it appears that Fusion AQX has issues connecting to the database or the connectivity data is not properly configured. To set it up, open the application and then check the connection settings. It's possible that you need to configure the connection info again. There is also the possibility that the server you're trying to connect to is in maintenance or not reachable.
Contact the server admin and he should provide additional information related to this issue.