QuickBooks Error 6123, 0 is a common issue that many users encounter when trying to open, upgrade, or restore their company files. This error can also occur while accessing files on a network. It can be a frustrating experience, but with the right troubleshooting steps, you can resolve the issue and get your QuickBooks software back on track. In this comprehensive guide, we'll explore the causes of QuickBooks Error 6123 and provide step-by-step solutions to fix it. We'll also discuss preventive measures to avoid this error in the future.