Hi all. I am PaulE. I have been working as a technical representative. Many users ask me what to do when they see QuickBooks Error H505. These error codes are most often encountered when the hosting configuration or configuration parameters need change or adjustment. The error can also be shown if an error occurs with the.ND file or when a computer's access is denied by network security software. When network security software denies access to a PC, the error is shown.