I have two tree caches in the cluster. Fllowing is the exception stacktrace . The last row has no more stacks, so it is versy strange. Who can help me ? java.lang.RuntimeException: java.lang.NullPointerException at org.jboss.cache.TreeCache.invokeMethod(TreeCache.java:5523) at org.jboss.cache.TreeCache.get(TreeCache.java:3468) at org.jboss.cache.TreeCache.get(TreeCache.java:3449) at com.primeton.eos.wf.service.instpool.treecache.optimize.WFInstancePoolOptimize.findProcessInstanceByID(WFInstancePoolOptimize.java:293) at com.primeton.eos.wf.service.instpool.treecache.optimize.WFInstancePoolOptimize.findProcessInstanceByID(WFInstancePoolOptimize.java:421) at com.primeton.eos.wf.service.api.systemlog.InstPoolSync.syncInner(InstPoolSync.java:100) at com.primeton.eos.wf.service.api.systemlog.InstPoolSync.sync(InstPoolSync.java:96) at com.primeton.eos.wf.service.api.systemlog.InstPoolSync.syncByWorkItemID(InstPoolSync.java:85) at com.primeton.eos.wf.engine.worklist.WorklistQueryManagerImpl.queryWorkItemByID(WorklistQueryManagerImpl.java:1079) at com.primeton.eos.wf.engxml.EngineXMLAdaptor.queryWorkItemByID(EngineXMLAdaptor.java:1662) at com.primeton.eos.wf.bizlet.WorklistQueryManager.BL_queryWorkItemByID(Unknown Source) ... 32 more Caused by: java.lang.NullPointerException View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4132065#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...