Using jbpm-server-7.25.0.Final-dist.zip 1) start jbpm with ./standalone.sh -Dorg.jbpm.ht.callback=props -Dorg.jbpm.ht.userinfo=props 2) login as wbadmin on BusinessCentral, and create a simple bpm (import attached sample) 3) start an instance process 4) login as jack (IT group). 5) Go to Task Inbox. Error with stacktrace is throw on the Console. The designed form didn't shows up. A default generated form is shown instead. PROPOSED FIX: Looking at GetUserTaskCommand.java:67 protected boolean checkUserPermissions( String userId, Task task, TaskContext context) { List< String > usersGroup = context.getUserGroupCallback().getGroupsForUser(userId); usersGroup.add(userId); userGroup is an inmmutable list, because JBossUserGroupCallbackImpl.getGroupsForUser(String) is returning an inmutable list. I propose a minor change into JBossUserGroupCallbackImpl.getGroupsForUser(String), to return a new ArrayList like this: public List< String > getGroupsForUser( String userId) { List< String > groups = groupStore.get(userId); if ( groups == null ) { groups = new ArrayList< String >(0); } return new java.util.ArrayList< String >(groups); // <-- changed from return groups; }