It is unclear what this means: "You need to register database connection on Services tab." Even though users have registered their database connection in the Services tab, they still get this message.
Ideally, there shouldn't be a problem that causes the above message. But if there is a legitimate problem, the message should be clearer and instruct correctly what should be done to avoid the problem.
See long list of comments on this here, in the comments:
*** This bug has been marked as a duplicate of bug 227148 ***