Transactions > Sales > Bill Sale Orders > Errors: "You can not initialize invoice: invalid reference XXXX" Or "You have an invalid sales order XXXX or the order is already closed."

Symptoms:
1. Trying to process bulk billing for sales orders containing inventory items and other charge/service/non-inventory items setup as Can Be Fulfilled/Received = False.
2. Setup > Accounting > Accounting Preferences > Order Management > Invoice In Advance of Fulfillment = False.
3. The inventory items are not fulfilled or partially fulfilled.
4. Status of the sales order is Pending Fulfillment.
5. Once they submit those orders for bulk billing, invoice/cash sales are not created with error logs of either:
"You can not initialize invoice: invalid reference XXXX" 
"You have an invalid sales order XXXX or the order is already closed." (where XXXX is the internal ID of the sales order).

Solution/Workaround:
Bulk billing is trying to bill the whole sales order including the unfulfilled inventory items. So, you can do either of the following options:
1. Individually bill the sales orders.
2. Set Invoice in Advance of Fulfillment to True at Setup > Accounting > Accounting Preferences > Order Management. (Please note though that this will bill the whole sales order including the unfulfilled inventory items.)

 Note:

This is currently logged under Enhancement 270768 : "Transactions > Sales > Bill Sales Orders > Receives Error " You can not initialize invoice: invalid reference xxxxx" or "You have an invalid sales order XXXX or the order is already closed" when billing a sales order"