When the QuickBooks Database Server Manager (QBDBMgrN) does not launch, multi-user mode access is not possible, resulting in the QBDBMgrN Not Running On This Computer problem. Firewall restrictions, an out-of-date QuickBooks version, or a deactivated service are frequently the causes. Restarting the service, upgrading QuickBooks, or adjusting firewall settings are some ways to fix it. If you have any problems, give the QB support team a call at 1.855.738.2784.