Solution : https://service.sap.com/sap/support/notes/707090 (SAP Service marketplace login required)
Key words :
system generates error message 06243 internal number assignment, internal number range, external document number, program error, number range, pleaseenter number, document type, call bapi_po_create1, purchase orders, purchase order
Related Notes :
| 798537 | BAPI_PO_CREATE1: ME083, although goods supplier filled |