What Is QuickBooks error H505 & How To Fix It? Error H505 in QuickBooks can take place when you try to access a company file that is not located on your computer. The error indicates that the company file needs an additional configuration. QuickBooks error H505 belongs to the multi-user mode error that is caused when something is blocking the multi-user connection to your server. There are various other reasons behind the QuickBooks error H505. In this post, we will discuss the possible reasons and some of the most effective troubleshooting solutions to resolve error code H505.