Error: "Credit note amount cannot exceed the total paid amount of the selected invoices"

Issue Description:

When attempting to issue a Credit Note against an invoice, the system blocks saving and returns the error:

Credit note amount cannot exceed the total paid amount of the selected invoices.

Root Cause Validation Rules:

1. Refund Credit Notes: Capped at Amount less than equal Paid Amount. You cannot issue a refund for cash that was never collected.

2. Adjustment Credit Notes: Capped at Amount less than equal Outstanding Amount (Total - Paid).
   
   

Resolution Steps:

• For Fully Unpaid Invoices:

  Change the Reason / Type dropdown on the CN creation page from Refund to Adjustment (or untick the Refund checkbox). Ensure the CN total matches the unpaid balance.

• For Partially Paid Invoices:

  1. Process a Refund CN for the exact amount received (Paid Amount).

  2. Process an Adjustment CN for the remaining balance (Outstanding Amount).