You may have a special character in a field which Quickbooks cannot process. This often happens in the line item description field so this is the first area we suggest for you to review. The following character can cause this error:
If you find the invoice has a special character in this field please reset ("Actions" -> "Reset") the invoice and remove the special characters.
Reset Invoices Guide
Note: If you are importing Purchase orders from Quickbooks into Beanworks then please instruct your PO creators not to use special characters in the line item description fields. As the PO line item description field will except special characters as where the invoice line item description does not.