Cannot create purchase receipt for item x with the existing serial number x

[abdulrafiqux]

I received this message, when trying to do a purchase return. Here’s what happened prior:

1. Raised PO
2. Raised Purchase invoice on the PO
3. Made 100% upfront payment on the Purchase Invoice
4. Raised Purchase receipt, rejected qty = 1 → serial no. for item created
5. Raised debit note against Purchase invoice
6. Raised Purchase return, rejected qty = -1 → received the error message