Solution : https://service.sap.com/sap/support/notes/450154 (SAP Service marketplace login required)
Key words : 
system displays error message vv401, attached source code corrections, error message vv400, dynamic assembly processing, respective production order, production order, assembly order', assembly order, sales order, transferring results
Related Notes : 
       
| 459262 | Change in quantity for sales order item with assembly | 
| 434532 | Dynamic assembly: Runtime for control of configuration | 
| 418767 | Dynamic assembly: BOM not exploded |