Solution : https://service.sap.com/sap/support/notes/39020 (SAP Service marketplace login required)
Key words :
error message cj021 'wbs element xxxxxxxxxxx, additional key words kb21, internal wbs element number, solution modify structure 'rkibi2b', respective data element, access transaction 'se11', data element 'eproj', 'rkibi2' dictionary objects, choose 'table -> activate', wbs element
Related Notes :
| 65467 | CATS: Additional changes relevant for HR |
| 45397 |