QuickBooks Error Code H505. typically occurs when you try to open the file from a workstation located on a Server or a Host Computer. This is also referred to as QuickBooks Multi-user Setup.ut, if you are unable to apply any of the above-given solutions, or if QuickBooks Error H505 does not get resolved, call us now at our QuickBooks Error Support Number +1-877-349-3776 to get instant troubleshooting.