Solution : https://service.sap.com/sap/support/notes/505174 (SAP Service marketplace login required)
Key words : 
credit-locked sales orders, arbgb /sapapo/atp msgnr 147, apo backorder processing, apo outbound queue, apo controller, /3 inbound queue, availability check, program error, solution implement, program corrections
Related Notes : 
       
| 776512 | |
| 530652 | |
| 485648 | |
| 375193 | Backorder processing: Composite SAP note on posting |