Solution : https://service.sap.com/sap/support/notes/1104496 (SAP Service marketplace login required)
Key words : 
transaction va01/va02, error processing control', message_type_x runtime error, runtime error, program error, navigation sequence, backend editor, message vx 205, internal errors', save texts
Related Notes : 
       
| 1083803 | Runtime error MESSAGE_TYPE_X when maintaining text | 
| 954372 | Short dump when navigating to text screen (troubleshooting) |