With version 4.1.5 the EnversPostUpdateEventListenerImpl.postUpdateDBState was introduced.
When you lock into the org.hibernate.engine.internal.TwoPhaseLoad.addUninitializedEntity(EntityKey, Object, EntityPersister, LockMode, boolean, SessionImplementor) method, you'll see that the loadedState is set to NULL.
Stacktrace
java.lang.NullPointerException
at org.hibernate.envers.event.EnversPostUpdateEventListenerImpl.postUpdateDBState(EnversPostUpdateEventListenerImpl.java:86)
at org.hibernate.envers.event.EnversPostUpdateEventListenerImpl.onPostUpdate(EnversPostUpdateEventListenerImpl.java:53)
at org.hibernate.action.internal.EntityUpdateAction.postUpdate(EntityUpdateAction.java:255)
at org.hibernate.action.internal.EntityUpdateAction.execute(EntityUpdateAction.java:212)
at org.hibernate.engine.spi.ActionQueue.execute(ActionQueue.java:362)
at org.hibernate.engine.spi.ActionQueue.executeActions(ActionQueue.java:354)
at org.hibernate.engine.spi.ActionQueue.executeActions(ActionQueue.java:276)
at org.hibernate.event.internal.AbstractFlushingEventListener.performExecutions(AbstractFlushingEventListener.java:326)
at org.hibernate.event.internal.DefaultFlushEventListener.onFlush(DefaultFlushEventListener.java:52)
at org.hibernate.internal.SessionImpl.flush(SessionImpl.java:1214)
at org.hibernate.internal.SessionImpl.managedFlush(SessionImpl.java:403)
at org.hibernate.engine.transaction.synchronization.internal.SynchronizationCallbackCoordinatorImpl.beforeCompletion(SynchronizationCallbackCoordinatorImpl.java:104)
at org.hibernate.engine.transaction.synchronization.internal.RegisteredSynchronization.beforeCompletion(RegisteredSynchronization.java:53)
at ...