Solution : https://service.sap.com/sap/support/notes/313120 (SAP Service marketplace login required)
Key words :
additional key words mm-pur, set account assignment category, account assignment category, select basic data, select entry pt9f, account assignment, optional entry, transaction me21n, purchase order, external services
Related Notes :
| 633986 | FAQ: Account assignment in the service |
| 439742 | ME51N: Account assignment category 'Unknown' during service |
| 360632 | ME21N Various improvements for account assignments |