We are supposed to be able to use TransactionSynchronizationRegistry.registerInterposedSynchronization (TSR) in our containers but I wanted to bring up an ordering issue that can happen. If you look at http://pastie.org/1836698, you can see what happened when Hibernate registered a synchronization object with the TSR and we tried after to get a database connection from the connection pool. Basically, once a synchronization object is registered with the TSR, the other way of registering a synchronization object through the Transaction registerSynchronization() cannot be used (or you get the above linked IllegalStateException error). The short term fix was to avoid registering Hibernate with the TSR and instead use the Transaction registerSynchronization(). This helped avoid the ISE exception as the TSR sync ordering check is avoided. The Transaction registerSynchronization(), has no ordering requirements but as we have seen, the TSR registerInterposedSynchronization does. I think we need to be consistent across our projects and either use TSR or avoid it (to avoid the "Synchronizations are not allowed!" JTA error). If/when we use it, we need to coordinate the switch over to it, so that all projects have time to switch to it. I'm hoping someone will tell me that there is an easier path to use TSR registerInterposedSynchronization in some of our projects. What do you think? The other question, is how/when we should we coordinate a switch over to use TSR (assuming there is agreement that we should coordinate the switch)? Scott