QuickBooks Error H505 is a common issue encountered by users. It typically occurs when QuickBooks is unable to establish a connection with the company file on another computer or server. This error can be caused by network issues, incorrect settings, or firewall restrictions. To resolve Error H505, users can try troubleshooting steps such as verifying network settings, configuring firewall permissions, and using the QuickBooks File Doctor tool. Seeking assistance from QuickBooks support or consulting technical resources can also help in resolving this error effectively.