The cause of OptionalDataException that was messing up state transfers is now fixed. However, "Initial state transfer failed" error was still popping up in some tests. The cause of this error is incorrect logic in TreeCache.startService related to fetching of in memory state. JBC can not fetch in memory state based only on FetchInMemoryState element but should rather use JBC 1.4 logic? protected boolean shouldFetchStateOnStartup() { return !configuration.isInactiveOnStartup() && buddyManager == null && (configuration.isFetchInMemoryState() || (cacheLoaderManager != null && cacheLoaderManager.isFetchPersistentState())); } When I use this approach "Initial state transfer failed" errors go away. State transfer tests now fail on: 1) Region exceptions org.jboss.cache.RegionNotEmptyException: Node / already exists and is not empty at org.jboss.cache.TreeCache.activateRegion(TreeCache.java:954) at 2) Activators Activator A caught an exception junit.framework.AssertionFailedError: Activator A caught an exception at org.jboss.cache.statetransfer.VersionedTestBase.concurrentActivationTest (VersionedTestBase.java:427) at org.jboss.cache.statetransfer.VersionedTestBase.testConcurrentActivation Sync(VersionedTestBase.java:353) 3) Buddy integration node /a/d not found (gtx=null, caller=Thread[main,5,main]) org.jboss.cache.NodeNotExistsException: node /a/d not found (gtx=null, caller=Thread[main,5,main]) at org.jboss.cache.TreeCache._put(TreeCache.java:2783) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)