Running JMeter 2.11 with Java 1.8.0_45 , I get this exception when recording a scenario using UbikLoadPack GWT Plugin for JMeter.
2016/02/04 12:03:48 ERROR - com.ubikingenierie.jmeter.plugin.gwt.renderer.RenderAsGwtRPCResponse: Exception converting to XML://OK[3,-6,2,0,12,12,0,0,-1,11,0,0,'VKq$9BG',0,0,0,0,12,12,6,11,0,10,9,8,7,1,6,0,5,0,1,0,0,0,0,0,0,0,1,10,4,0,1,1,'A',3,0,2,0,0,0,0,30,'A',0,1,["com.edgenius.wiki.gwt.client.model.UserModel/3228739334","anonymous user","anonymous","[I/2970817851","/static/images/noportrait.jpg","java.util.ArrayList/4159755760","com.edgenius.wiki.gwt.client.model.RoleModel/1814311428","unregister users group","Public","ROLE_SYS_ANONYMOUS","java.lang.Integer/3438268394",""],0,7], message:-1 java.lang.ArrayIndexOutOfBoundsException: -1
at com.thoughtworks.xstream.core.util.OrderRetainingMap.entrySet(OrderRetainingMap.java:77)
at java.util.HashMap.putMapEntries(Unknown Source)
at java.util.HashMap.putAll(Unknown Source)
at com.thoughtworks.xstream.core.util.OrderRetainingMap.<init>(OrderRetainingMap.java:36)
at com.thoughtworks.xstream.converters.reflection.FieldDictionary.buildMap(FieldDictionary.java:135)
at com.thoughtworks.xstream.converters.reflection.FieldDictionary.fieldsFor(FieldDictionary.java:76)
at com.thoughtworks.xstream.converters.reflection.PureJavaReflectionProvider.visitSerializableFields(PureJavaReflectionProvider.java:126)
at com.thoughtworks.xstream.converters.reflection.AbstractReflectionConverter.doMarshal(AbstractReflectionConverter.java:81)
at com.thoughtworks.xstream.converters.reflection.AbstractReflectionConverter.marshal(AbstractReflectionConverter.java:72)
at com.thoughtworks.xstream.core.AbstractReferenceMarshaller.convert(AbstractReferenceMarshaller.java:69)
at com.thoughtworks.xstream.core.TreeMarshaller.convertAnother(TreeMarshaller.java:58)
at com.thoughtworks.xstream.core.AbstractReferenceMarshaller$1.convertAnother(AbstractReferenceMarshaller.java:84)
at com.thoughtworks.xstream.converters.reflection.AbstractReflectionConverter.marshallField(AbstractReflectionConverter.java:229)
at com.thoughtworks.xstream.converters.reflection.AbstractReflectionConverter$2.writeField(AbstractReflectionConverter.java:208)
at com.thoughtworks.xstream.converters.reflection.AbstractReflectionConverter$2.<init>(AbstractReflectionConverter.java:171)
at com.thoughtworks.xstream.converters.reflection.AbstractReflectionConverter.doMarshal(AbstractReflectionConverter.java:116)
at com.thoughtworks.xstream.converters.reflection.AbstractReflectionConverter.marshal(AbstractReflectionConverter.java:72)
at com.thoughtworks.xstream.core.AbstractReferenceMarshaller.convert(AbstractReferenceMarshaller.java:69)
at com.thoughtworks.xstream.core.TreeMarshaller.convertAnother(TreeMarshaller.java:58)
at com.thoughtworks.xstream.core.TreeMarshaller.convertAnother(TreeMarshaller.java:43)
at com.thoughtworks.xstream.core.TreeMarshaller.start(TreeMarshaller.java:82)
at com.thoughtworks.xstream.core.AbstractTreeMarshallingStrategy.marshal(AbstractTreeMarshallingStrategy.java:37)
at com.thoughtworks.xstream.XStream.marshal(XStream.java:895)
at com.thoughtworks.xstream.XStream.marshal(XStream.java:884)
at com.ubikingenierie.jmeter.plugin.gwt.xml.GwtXmlConverter.a(GwtXmlConverter.java:71)
at com.ubikingenierie.jmeter.plugin.gwt.xml.GwtXmlConverter.a(GwtXmlConverter.java:53)
at com.ubikingenierie.jmeter.plugin.gwt.renderer.RenderAsGwtRPCResponse.a(RenderAsGwtRPCResponse.java:70)
at com.ubikingenierie.jmeter.plugin.gwt.renderer.RenderAsGwtRPCResponse.renderResult(RenderAsGwtRPCResponse.java:36)
at org.apache.jmeter.visualizers.ViewResultsFullVisualizer.valueChanged(ViewResultsFullVisualizer.java:253)
at javax.swing.JTree.fireValueChanged(Unknown Source)
at javax.swing.JTree$TreeSelectionRedirector.valueChanged(Unknown Source)
at javax.swing.tree.DefaultTreeSelectionModel.fireValueChanged(Unknown Source)
at javax.swing.tree.DefaultTreeSelectionModel.notifyPathChange(Unknown Source)
at javax.swing.tree.DefaultTreeSelectionModel.setSelectionPaths(Unknown Source)
at javax.swing.tree.DefaultTreeSelectionModel.setSelectionPath(Unknown Source)
at javax.swing.JTree.setSelectionPath(Unknown Source)
at javax.swing.plaf.basic.BasicTreeUI.selectPathForEvent(Unknown Source)
at javax.swing.plaf.basic.BasicTreeUI$Handler.handleSelection(Unknown Source)
at javax.swing.plaf.basic.BasicTreeUI$Handler.mousePressed(Unknown Source)
at java.awt.Component.processMouseEvent(Unknown Source)
at javax.swing.JComponent.processMouseEvent(Unknown Source)
at java.awt.Component.processEvent(Unknown Source)
at java.awt.Container.processEvent(Unknown Source)
at java.awt.Component.dispatchEventImpl(Unknown Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.LightweightDispatcher.retargetMouseEvent(Unknown Source)
at java.awt.LightweightDispatcher.processMouseEvent(Unknown Source)
at java.awt.LightweightDispatcher.dispatchEvent(Unknown Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Window.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
at java.awt.EventQueue.access$500(Unknown Source)
at java.awt.EventQueue$3.run(Unknown Source)
at java.awt.EventQueue$3.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
at java.awt.EventQueue$4.run(Unknown Source)
at java.awt.EventQueue$4.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
at java.awt.EventQueue.dispatchEvent(Unknown Source)
at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.run(Unknown Source)
This issue is due to the Usage of JMeter 2.11 with Java 8.
JMeter is compatible with Java 8 only starting from JMeter 2.12, so you need to upgrade to JMeter 2.12 and even better to most recent supported version of JMeter which is as of this writing JMeter 2.13.