Solution : https://service.sap.com/sap/support/notes/1538070 (SAP Service marketplace login required)
Key words :
bapi /afs/bapi_material_savedata, tab correction instruction, type j3amat, error message 82479, invalid input, j_3apghd reason, program error, client copy, grid material, prerequisites reason
Related Notes :
329719 | Creating a 'NO GRID' material is not possible |