This is a very similar issue to Kibana 6.1.0. and newer starts with error
I tried starting kibana version 6.2.3 (with x-pack installed) as a service, manually unsuccessfully, both times making sure the working directory is kibana_home (d:\ELK\apps\kibana-6.2.3-windows-x86_64) not the bin directory. I also removed the "optimize" directory without success.