Scenario
Saving a Transaction gets an error of “Posting and non-posting discounts/markups are not allowed on the same transaction”
Solution
By design, the system will not allow a Transaction with either two or more Discount or Markup items that are both a posting and non-posting account to be saved.
This is covered by Enhancement # 156967 – Please have the ability to add a non posting discount and a posting discount on the same transaction.
To be able to save the transaction, choose only one type of Discount/Markup items – either posting or non-posting.
>Open the two Discount/Markup items and take note under Accounting Tab what Account is set.