I have seen this before as well but never really figured it out.
Is the task reserved or inprogress?
Also, did the process throw any exceptions from script or service tasks?
I tried with Ready and Reserved status, but with no luck, still got
INFO [org.jbpm.services.task.wih.LocalHTWorkItemHandler] (http--0.0.0.0-8080-1) User '[UserImpl:'Administrator']' does not have permissions to execute operation 'Exit' on task id 30922
According to this http://docs.jboss.org/jbpm/v6.0.1/userguide/images/TaskService/WSHT-lifecycle.png I can do 'Exit' on each task status.
Does anyone know what cause the problem?
check if Administrator is actually assigned to your task as business administrator as that would cause the issue. Assignment might be done via groups (Administratos) so then Administrator needs to be member of that group.
Thank you Maciej, that solves the issue.