Solution : https://service.sap.com/sap/support/notes/534568 (SAP Service marketplace login required)
Key words :
'final sizing/determination' function, avoid long upgrade runtimes, ekpo-j_3adat field, j_3adat field, table ekpo, longer filled, terms me21, me22n reason, longer supported, prerequisites
Related Notes :
| 934129 | FAQ's on AFS-Purchasing |
| 536840 | AFS: EKPO-J_3ADAT is initial |