ElasticSearch Bulk Insert

Trying to connect to Elasticsearch (localhost:9200 or 9300). Any idea why this error?

An unexpected error occurred in Spoon:
Could not initialize class org.elasticsearch.threadpool.ThreadPool
java.lang.NoClassDefFoundError: Could not initialize class org.elasticsearch.threadpool.ThreadPool
at org.elasticsearch.client.transport.TransportClient$Builder.build(TransportClient.java:133)
at org.pentaho.di.ui.trans.steps.elasticsearchbulk.ElasticSearchBulkDialog.test(ElasticSearchBulkDialog.java:923)
at org.pentaho.di.ui.trans.steps.elasticsearchbulk.ElasticSearchBulkDialog.access$300(ElasticSearchBulkDialog.java:86)
at org.pentaho.di.ui.trans.steps.elasticsearchbulk.ElasticSearchBulkDialog$7.handleEvent(ElasticSearchBulkDialog.java:358)
at org.eclipse.swt.widgets.EventTable.sendEvent(Unknown Source)
at org.eclipse.swt.widgets.Display.sendEvent(Unknown Source)
at org.eclipse.swt.widgets.Widget.sendEvent(Unknown Source)
at org.eclipse.swt.widgets.Display.runDeferredEvents(Unknown Source)
at org.eclipse.swt.widgets.Display.readAndDispatch(Unknown Source)
at org.pentaho.di.ui.spoon.Spoon.readAndDispatch(Spoon.java:1375)
at org.pentaho.di.ui.spoon.Spoon.waitForDispose(Spoon.java:8104)
at org.pentaho.di.ui.spoon.Spoon.start(Spoon.java:9466)
at org.pentaho.di.ui.spoon.Spoon.main(Spoon.java:701)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.pentaho.commons.launcher.Launcher.main(Launcher.java:92)