QuickBooks Connection Diagnostic Tool is a great tool to solve network issues, data file damages and several other problems that commonly occur in QuickBooks. QB Diagnostic Tool works amazingly in a multi-user environment. You can easily detect the errors that will happen in the company files shared across the server. It is important to upgrade the tool to the latest version to avoid any security issues. The tool is available only for the QuickBooks versions for the Windows and is not available for the MAC Versions. What issues can QuickBooks Connection Diagnostic Tool resolve? You can use QuickBooks Diagnostic Tool to rectify the below errors. Access Denial to QuickBooks Database. Poorly configured Windows firewall. Various unexpected QuickBooks Errors: Errors: -6150, -6000, -82, -6000, -301, -6147 and -6130. The vendor list turned blank in your software.