Solution : https://service.sap.com/sap/support/notes/429586 (SAP Service marketplace login required)
Key words : 
additional key words sapscript, import support package sapkh45b44, blended code page, function module nls_get_frontend_cp, correction contained, special characters, upgrade phase, solution implement, correction attached, note 417453
Related Notes : 
       
| 439275 | PC editor: Systems with blended code page (4.6B) | 
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| 417453 | PC editor: Systems with blended code page |