You get the QBDBMGRN Not Running on this Computer issue when you try to install a QuickBooks update. This also happens if you try to upgrade QuickBooks to a newer version when the Windows firewall is still not updated. As a result, the firewall flags QBDBMgrN as an unknown service and prohibits it from accessing the internet. Furthermore, this error notice appears when you use QuickBooks File Doctor to fix your corporate file and network.