In http://community.jboss.org/thread/142942?tstart=0 I've been told that JBOSS 4.2.3GA comes with JBossTS 4.2.3.SP7.

We managed to see this exception with JBoss 4.2.3GA :

Caused by: java.lang.NullPointerException
at com.arjuna.ats.arjuna.coordinator.TwoPhaseCoordinator.beforeCompletion(TwoPhaseCoordinator.java:235)
at com.arjuna.ats.arjuna.coordinator.TwoPhaseCoordinator.end(TwoPhaseCoordinator.java:86)
at com.arjuna.ats.arjuna.AtomicAction.commit(AtomicAction.java:177)
at com.arjuna.ats.internal.jta.transaction.arjunacore.TransactionImple.commitAndDisassociate(TransactionImple.java:1389)
at com.arjuna.ats.internal.jta.transaction.arjunacore.BaseTransaction.commit(BaseTransaction.java:135)
at com.arjuna.ats.jbossatx.BaseTransactionManagerDelegate.commit(BaseTransactionManagerDelegate.java:87)
at org.jboss.tm.usertx.client.ServerVMClientUserTransaction.commit(ServerVMClientUserTransaction.java:140)
at com.artnology.managedobject.impl.ManagedObjectManager.commitUnderlyingTx(ManagedObjectManager.java:5292)
at com.artnology.managedobject.impl.ManagedObjectManager.commitTransaction(ManagedObjectManager.java:4838)

What's a bit unusual about our transaction is that it does a lot of work during beforeCompletion, which might exceed the transaction timeout (but I don't know for sure that it did). Maybe a long user code activity during beforeCompletion can cause this confusion of _synchs possibly already having been nulled out.