Solution : https://service.sap.com/sap/support/notes/490482 (SAP Service marketplace login required)
Key words : 
/ important general remarks ii/ error, upgrade guide iii/ additional actions, 'targetserverrole' sql server database role, dbs/mss/dbname profile parameter, \usr\sap\put\exe directory, iv/ problems/additional actions, prerequisites incomplete upgrade guide, sys\exe\run directory, upgrade guideiii/ additional actions, transferring sap kernel patches
Related Notes : 
       
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| 517070 | Enhancements to upgrading to SAP R/3 Enterprise 4.70 MSSQL | 
| 516206 | Shadow system: SQL229 | 
| 484876 | Additional information about upgrading to SAP Web AS 6.20 | 
| 19466 | Downloading SAP kernel patches |