Solution : https://service.sap.com/sap/support/notes/737115 (SAP Service marketplace login required)
Key words : 
bind sap_basis 640 support packages till, upgrade iv/ problems/additional actions, upgrade guideiii/ additional actions, prerequisites incomplete upgrade guide, ms sql server reason, correct upgrade fix buffer, ms sql server, ms sql server 2005, symptom additional information, scm41 srm40 ecc50
Related Notes : 
       
| 788623 | Additions to upgrade on SAP SRM Server 5.0 SR1 | 
| 788218 | Add. info. on upgrading to SAP ERP Central Component 5.0 SR1 | 
| 689574 | Add. info. on upgrading to SAP ERP Central Component 5.00 | 
| 684406 | Additional information on upgrading to SAP SCM 4.1 | 
| 490482 | Add. info on upgrading to SAP Web AS 6.20 MS SQL Server |