I've configured all required AR setups for the Business Unit and customer. I tried to create manual AR invoice and the form is error Java.Null pointer error.
Navigation:
Billing ----> Click Create Invoice ( Encountered error at this stage)
There is a bug in the page, unless and until you do not assign any business unit to that user, that page throws an error.
Solution - Assign a business unit using manage data access for users task and try again.