That error means that the UI can't talk to the database. This can happen when the database is not running or if it is really busy, which looks to be the case with yours. You wouldn't be able to log in if the database wasn't running. If you recently upgraded, it could be doing a rebuild in the background and it should be temporary. You may want to check out the task manager under ESM Management | Maintenance | Task Manager or take a look at /var/log/messages and top for any signs of an error. Thanks.