JBPM runtime throws below error while executing action task with MVEL dialect.

java.lang.RuntimeException: unable to execute Action
at org.jbpm.workflow.instance.node.ActionNodeInstance.internalTrigger(ActionNodeInstance.java:49)
at org.jbpm.workflow.instance.impl.NodeInstanceImpl.trigger(NodeInstanceImpl.java:122)
at org.jbpm.workflow.instance.impl.NodeInstanceImpl.triggerConnection(NodeInstanceImpl.java:185)
at org.jbpm.workflow.instance.impl.NodeInstanceImpl.triggerCompleted(NodeInstanceImpl.java:150)
at org.jbpm.workflow.instance.node.StartNodeInstance.triggerCompleted(StartNodeInstance.java:49)
at org.jbpm.workflow.instance.node.StartNodeInstance.internalTrigger(StartNodeInstance.java:41)
at org.jbpm.workflow.instance.impl.NodeInstanceImpl.trigger(NodeInstanceImpl.java:122)
at org.jbpm.ruleflow.instance.RuleFlowProcessInstance.internalStart(RuleFlowProcessInstance.java:35)
at org.jbpm.process.instance.impl.ProcessInstanceImpl.start(ProcessInstanceImpl.java:188)
at org.jbpm.workflow.instance.impl.WorkflowProcessInstanceImpl.start(WorkflowProcessInstanceImpl.java:302)
at org.jbpm.process.instance.ProcessRuntimeImpl.startProcess(ProcessRuntimeImpl.java:124)
at org.jbpm.process.instance.ProcessRuntimeImpl.startProcess(ProcessRuntimeImpl.java:105)
at org.drools.common.AbstractWorkingMemory.startProcess(AbstractWorkingMemory.java:1094)
at org.drools.impl.StatefulKnowledgeSessionImpl.startProcess(StatefulKnowledgeSessionImpl.java:297)
at com.sample.ProcessTest.main(ProcessTest.java:48)
Caused by: java.lang.ClassCastException: org.mvel2.compiler.ExecutableAccessor cannot be cast to org.mvel2.compiler.CompiledExpression
at org.jbpm.process.instance.impl.MVELAction.execute(MVELAction.java:117)
at org.jbpm.workflow.instance.node.ActionNodeInstance.internalTrigger(ActionNodeInstance.java:47)
... 14 more