QuickBooks Error H505 occurs when switching to multi-user mode, indicating issues with accessing the company file on another computer. This error typically arises due to improper hosting configuration, blocked communication by the firewall, or DNS settings issues. Resolving Error H505 involves verifying network connectivity, configuring firewall settings, ensuring proper hosting setup, and checking DNS settings to facilitate seamless multi-user access and collaboration within QuickBooks. For immediate assistance, please contact our QuickBooks Experts Team at 1.855.409.2300.