“QBDBMgrN Not Running on this Computer” is a general error message that appears when a user tries to run QuickBooks in multi-user mode and QuickBooks database server manager is not running on the system. In the linked article you can find every possible reason for the occurrence of the error along with some top troubleshooting methods. You can also reach QuickBooks support for troubleshooting help at 1.800.579.0391.