QuickBooks is a powerful accounting software used by millions of businesses worldwide. However, like any software, it is not immune to errors. One common issue users face is QuickBooks Error 12002. This error generally occurs when QuickBooks fails to access the server due to internet connectivity issues, firewall settings, or other network-related problems. In this guide, we will delve into the causes of QuickBooks Error 12002 and provide comprehensive, step-by-step solutions to resolve it.