Solution : https://service.sap.com/sap/support/notes/372123 (SAP Service marketplace login required)
Key words : 
error message /sapapo/atp_bop 035 'updating, higher-level main item, additional key words transaction, attached source code corrections, repeated rule evaluation, prerequisites solution implement, exitbackorder processing completely, /sapapo/bop_resultbackorder processing, requested delivery date, backorder processing status
Related Notes : 
       
| 400517 | Backorder processing: Deadlines are not transferred | 
| 385472 | Backordr procss.:do not transfer items w/ cancelld confirmtn | 
| 375193 | Backorder processing: Composite SAP note on posting | 
| 371396 | Update of BOP results |