When QuickBooks is unable to establish a connection to the company file in a multi-user environment, "QuickBooks Error H505" is a common error code that appears. It suggests that there is an issue with the network setup or configuration, which prevents the workstation from accessing the corporate file that is kept on another computer. To fix this error and get QuickBooks' multi-user functionality back, verify firewall permissions, modify host file settings, troubleshoot network settings, and more. 1.855.738.2784's QuickBooks Experts Team is available right away if you need help.