An Error Occured While Processing This Transaction. All Processing Was Rolled Back
This error occurs when processing a Purchase Order.
Reason and Solution
Check the Order defaults on the Purchase Order Tab the correct transaction types have been selected, however on the Inventory Defaults | Goods Received Vouchers Tab, the transaction types are blank as per screen shot below.
Select the correct transaction types as per the order defaults, then process, should allow the process to go through with no errors.