"QBCFMonitorService Not Running On This Computer" is an error that prevents QuickBooks from supporting multiple users together. This tutorial offers suggestions on how to restart the service. We'll look into updating QuickBooks, starting up and verifying the service again, and checking network connectivity. If needed, we'll look into adjusting firewall settings, resolving software conflicts, and repairing your QuickBooks installation. The QuickBooks File Doctor tool is the last option for locating the issue. With these procedures, you should be able to fix the problem and get back seamless multi-user access in QuickBooks.