Solution : https://service.sap.com/sap/support/notes/1701575 (SAP Service marketplace login required)
Key words : 
central instance / primary application server instance, dialog instance / additional application server instance, dialog instance / additional application server fails, additional application server instance reason, solution manager diagnostics agent, /sapinst sapinst_skip_errorstep=true               windows, sap netweaver process integration 7, existing sap system based, dialog instance, additional instance
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