Error when attempting to customize Invoice form: "Sorry, the invoice has no detail lines and will be backed out. Please re-create invoice."
This error occurs due to the fact the Forms Editor program needs to have the proper data available in order to present a "preview" of a form that is being edited. In the case of the Invoice form, the system must be able to access invoice data in order to pre-load the Forms Editor program with the data fields necessary to support the preview function.
So before you can edit the Invoice form, you will need to open the Sales Order screen for a Sales Order that has had an invoice created, and go to the Shipping & Invoicing sub-tab, then click on the Invoicing sub-tab there to access the invoice listing for that Sales Order.
At that point, the Forms Editor program will have access to the Invoice data, and will allow you to edit the Invoice form without presenting this error.
In the event that you have chosen to edit/customize forms during a new installation before actual invoice data exists, you will want to open the DBA Sample Company with the Red Wagon example, so you can edit your form in that install, and not create false invoicing transactions in your live database. Any customized and saved form with an unique name will be available in your DBA Main Company.