I can confirm that i get the same behaviour on hot-deploy with jboss4.0.4GA. The 4.0.3SP1 worked fine. I fear that a connection used previously is still somehow associated with a transaction, and on hotdeploy the connection is (re) associated with the transaction which causes the oracle XAResource problems...... Any ideas? Caused by: org.jboss.resource.JBossResourceException: Could not enlist in transaction on entering meta-aware object!; - nested throwable: (javax.transaction.SystemException: java.lang.Throwable: Unabled to enlist resource, see the previous warnings. tx=TransactionImpl:XidImpl[FormatId=257, GlobalId=klauser/8, BranchQual=, localId=8]) at org.jboss.resource.connectionmanager.TxConnectionManager.managedConnectionReconnected(TxConnectionManager.java:329) at org.jboss.resource.connectionmanager.BaseConnectionManager2.reconnectManagedConnection(BaseConnectionManager2.java:501) at org.jboss.resource.connectionmanager.BaseConnectionManager2.allocateConnection(BaseConnectionManager2.java:382) at org.jboss.resource.connectionmanager.BaseConnectionManager2$ConnectionManagerProxy.allocateConnection(BaseConnectionManager2.java:812) at org.jboss.resource.adapter.jdbc.WrapperDataSource.getConnection(WrapperDataSource.java:88) ... 194 more Caused by: javax.transaction.SystemException: java.lang.Throwable: Unabled to enlist resource, see the previous warnings. tx=TransactionImpl:XidImpl[FormatId=257, GlobalId=klauser/8, BranchQual=, localId=8] at org.jboss.resource.connectionmanager.TxConnectionManager$TxConnectionEventListener$TransactionSynchronization.checkEnlisted(TxConnectionManager.java:728) at org.jboss.resource.connectionmanager.TxConnectionManager$TxConnectionEventListener.enlist(TxConnectionManager.java:561) at org.jboss.resource.connectionmanager.TxConnectionManager.managedConnectionReconnected(TxConnectionManager.java:323) ... 198 more, userData={null} ]}, ackState=false, ackTime=0, ackUser=null, ackSystem=null ], handback: null View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=3963483#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...