We play with starting/stopping the TransactionManager during our testsuite... And we use different ObjectStores for each time we start another TransactionManager, by doing: System.setProperty(com.arjuna.ats.arjuna.common.Environment.OBJECTSTORE_DIR, newObjectStore + new GUID().toString()); I have already tried to create XidImple only after starting the TransactionManager and I still get a failure.... I will investigate this. Thanks Mark! View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4082204#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...