To fix QuickBooks errors 6189 and 816, start by ensuring QuickBooks Desktop is updated. Next, rename the.TLG and . ND files associated with your company file. Check network connectivity and permissions. Run the QuickBooks Database Server Manager to rescan the company file folder. Verify firewall settings to allow QuickBooks connections. Ensure all users are using the same QuickBooks version. If the errors persist, you can also contact our experts by dialing us at +1 855-856-0053 and we will provide you with instant technical assistance.