Scott has verified that the failure he is seeing involves 2 synchronizations. The first is from EntityManagerImpl and the second is HSearch. The problem is that the EntityManagerImpl (anonymous) Synchronization.afterCompletion() closes the session, which in turn, calls TransactionCoordinatorImpl.close() which calls reset(), which clears the synchronizations from the registry. After that finishes, SynchronizationRegistryImpl.notifySynchronizationsAfterTransactionCompletion() attempts to execute HSearch afterCompletion() synchronization, but the registry has already been cleared, resulting in the ConcurrentModificationException. I initially thought a possible fix would be to defer calling TransactionCoordinatorImpl.reset() if the afterCompletion() synchronizations are being executed. Doing this would be fairly straightforward. The problem is that, since the EntityManager afterCompletion() synchronization is executed first, the session would be closed before the HSearch afterCompletion() synchronization is executed. I mentioned this to Sanne and he said that the HSearch afterCompletion() synchronization might need access to the persistence context to, for example, initialize a collection, or to get entity state. Obviously it can't if the session is already closed. Is there a reason why the EntityManager synchronization is registered before the HSearch synchronization? Is there a way to always make the "session-closing" synchronization last? Steve, do you see a better way around this? Thanks, Gail _______________________________________________ hibernate-dev mailing list hibernate-dev(a)lists.jboss.org https://lists.jboss.org/mailman/listinfo/hibernate-dev