Solution : https://service.sap.com/sap/support/notes/1301466 (SAP Service marketplace login required)
Key words : 
<upg_dir>/sdt/exe byexec $java_cmd -cp, proper error handling assertion errors, lineexec $java_cmd -ea -cp, $gui_java_opts sdtgui $servopt $portopt, terms dsugui, assertions reason, prerequisites due, starting script, assertions switched, solution replace
Related Notes : 
       
| 1362176 | Upgrade to SAP NW 7.1 EHP 1 for banking services 7.0 and 8.0 | 
| 1252365 | Upgrades based on SAP NetWeaver 7.1 including EHP 1 |