Hi, I checked the version of the drools-guvnor, it was 5.0 and of drools is 5.1, So I downloaded the drools-guvnor 5.1 candidate release and from there I downloaded the ChangeSet.xml file and replaced the one I had used it before. But still m getting the same exception. Exception is : 2010:07:208 12:07:201:debug] KnowledgeAgent rebuilding KnowledgeBase using ChangeSet 2010:07:208 12:07:201:debug] KnowledgeAgent building resource=[UrlResource path='http://172.17.88.140:8441/drools-guvnor/org.d ools.guvnor.Guvnor/package/payRoll_pradeep/LATEST'] 2010:07:208 12:07:217:exception] java.lang.RuntimeException: KnowledgeAgent exception while trying to deserialize KnowledgeDefinitionsPackage at org.drools.agent.impl.KnowledgeAgentImpl.rebuildResources(KnowledgeAgentImpl.java:425) at org.drools.agent.impl.KnowledgeAgentImpl.applyChangeSet(KnowledgeAgentImpl.java:121) at org.drools.agent.impl.KnowledgeAgentImpl.applyChangeSet(KnowledgeAgentImpl.java:110) at org.ofbiz.drools.event.drool.RuleIntegrate.createKnowledgeBase(RuleIntegrate.java:45) at org.ofbiz.drools.event.drool.RuleIntegrate.createWorkingMemory(RuleIntegrate.java:29) at org.ofbiz.payRoll.PayRollTax.callPayRollTaxRule(PayRollTax.java:23) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) . . . Caused by: java.net.SocketException: Unexpected end of file from server at sun.net.www.http.HttpClient.parseHTTPHeader(HttpClient.java:769) at sun.net.www.http.HttpClient.parseHTTP(HttpClient.java:632) at sun.net.www.http.HttpClient.parseHTTPHeader(HttpClient.java:766) at sun.net.www.http.HttpClient.parseHTTP(HttpClient.java:632) at sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1000) at org.drools.io.impl.UrlResource.grabStream(UrlResource.java:154) at org.drools.io.impl.UrlResource.getInputStream(UrlResource.java:102) at org.drools.agent.impl.KnowledgeAgentImpl.rebuildResources(KnowledgeAgentImpl.java:414) Please help me in this, If I am missing something. Thanks & Regards Pradeep Ruhil Hi, Which version of drools are you using? Make sure you are using the same version in guvnor and in your application. Best, El jul 26, 2010 7:48 a.m., "Pardeep Ruhil" <Pardeep.Ruhil(a)lntinfotech.com&gt; escribi?: Hi, ________________________________ This Email may contain confidential or privileged information for the intended recipient (s) If you are not the intended recipient, please do not use or disseminate the information, notify the sender and delete it from your system. ______________________________________________________________________