I have a problem, which should be simple to solve, but i can't find the method to call to solve this problem: My problem is, that every Task Event (org.activiti.engine.task.Event) returnes null by calling Event.getUserId(); If I take a look into the database I see that the database table ACT_HI_COMMENT has null as value for the column USER_ID_ for every row. I generate these TaskEvents programmatically by calling (for example) processEngine.getTaskService().addComment(task.getId(), null, commentMessage); processEngine.getTaskService().addUserIdentityLink(task.getId(), user.getId(), IDENTITY_LINK_OBSERVER); I guess there is a simple method that I must call to solve this problem, something like processEngine.setCurrentUser(authenticatedUser.getId()); Any suggestions?