Failed to load plugin class[elasticsearch.authenticate.AuthenticatePlugin]

[kumar_prasad]

elasticsearch fails to start, i see the below error
Caused by: java.lang.ClassCastException: java.util.LinkedHashMap cannot be cast to java.util.ArrayList
at com..elasticsearch.authenticate.accesscontrol.utils.ConfigReader.buildRolesCache(ConfigReader.java:78) ~[?:?]
at com..elasticsearch.authenticate.accesscontrol.AccessControlCache.(AccessControlCache.java:76) ~[?:?]
at com..elasticsearch.authenticate.AuthenticatePlugin.(AuthenticatePlugin.java:86) ~[?:?]
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) ~[?:?]
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62) ~[?:?]
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) ~[?:?]
at java.lang.reflect.Constructor.newInstance(Constructor.java:423) ~[?:1.8.0_221]
at org.elasticsearch.plugins.PluginsService.loadPlugin(PluginsService.java:556) ~[elasticsearch-6.2.2.jar:6.2.2]
at org.elasticsearch.plugins.PluginsService.loadBundle(PluginsService.java:505) ~[elasticsearch-6.2.2.jar:6.2.2]
at org.elasticsearch.plugins.PluginsService.loadBundles(PluginsService.java:422) ~[elasticsearch-6.2.2.jar:6.2.2]
at org.elasticsearch.plugins.PluginsService.(PluginsService.java:146) ~[elasticsearch-6.2.2.jar:6.2.2]
at org.elasticsearch.node.Node.(Node.java:303) ~[elasticsearch-6.2.2.jar:6.2.2]
at org.elasticsearch.node.Node.(Node.java:246) ~[elasticsearch-6.2.2.jar:6.2.2]
at org.elasticsearch.bootstrap.Bootstrap$5.(Bootstrap.java:213) ~[elasticsearch-6.2.2.jar:6.2.2]
at org.elasticsearch.bootstrap.Bootstrap.setup(Bootstrap.java:213) ~[elasticsearch-6.2.2.jar:6.2.2]
at org.elasticsearch.bootstrap.Bootstrap.init(Bootstrap.java:323) ~[elasticsearch-6.2.2.jar:6.2.2]
at org.elasticsearch.bootstrap.Elasticsearch.init(Elasticsearch.java:121) ~[elasticsearch-6.2.2.jar:6.2.2]

[DavidTurner]

elasticsearch.authenticate.AuthenticatePlugin is not part of Elasticsearch so I'm guessing it's a third-party plugin which is not compatible with this version of Elasticsearch. You'll need to contact the supplier of that plugin for help.