Mahara: Site unavailable

Mahara could not connect to the application database.

* If you are using Mahara, please wait a minute and try again
* If you are the administrator, please check your database settings and make sure your database is available

The error received was:
mysql error: [2005: Unknown MySQL server host '' (1)] in CONNECT(, 'dbo391416218', '****', db391416218)