Quickbooks Error -6123,0 An Error occurred when QuickBooks tried to start database server

This error indicates a firewall of some sort is blocking Quickbooks communicating between the workstation and the server hosting the Data Manager.

This can be a hardware firewall such as a cable or DSL router/firewall. This can also be caused by software firewalls such as Norton Personal Firewall, McAfee's firewall, SmartFirewall, or any firewall utility built into an antivirus program.