This is sort of a repost of an error I’ve been getting, but I thought with the new year, I’d give it another shot.

I’ve been getting the following exception in my code:

[2010:12:361 09:12:910:debug] KnowledgeAgent rebuilding KnowledgeBase using ChangeSet

[2010:12:361 09:12:972:exception]

***java.lang.RuntimeException*: KnowledgeAgent exception while trying to deserialize KnowledgeDefinitionsPackage

  at org.drools.agent.impl.KnowledgeAgentImpl.createPackageFromResource(***KnowledgeAgentImpl.java:664*)

  at org.drools.agent.impl.KnowledgeAgentImpl.addResourcesToKnowledgeBase(***KnowledgeAgentImpl.java:889*)

  at org.drools.agent.impl.KnowledgeAgentImpl.rebuildResources(***KnowledgeAgentImpl.java:704*)

  at org.drools.agent.impl.KnowledgeAgentImpl.buildKnowledgeBase(***KnowledgeAgentImpl.java:584*)

  at org.drools.agent.impl.KnowledgeAgentImpl.applyChangeSet(***KnowledgeAgentImpl.java:185*)

  at org.drools.agent.impl.KnowledgeAgentImpl.applyChangeSet(***KnowledgeAgentImpl.java:168*)

  at com.agencyawards2.RuleSessionProviderFactory.getSessionFactory(***RuleSessionProviderFactory.java:95*)

  at com.agencyawards2.RuleSessionProviderFactory.getProvider(***RuleSessionProviderFactory.java:35*)

  at com.agencyawards2.RunRules.runRules(***RunRules.java:27*)

  at com.agencyawards2.DroolsTest.main(***DroolsTest.java:40*)

Caused by:*** java.io.StreamCorruptedException*: invalid stream header: 7061636B

  at java.io.ObjectInputStream.readStreamHeader(Unknown Source)

  at java.io.ObjectInputStream.<init>(Unknown Source)

  at org.drools.common.DroolsObjectInputStream.<init>(***DroolsObjectInputStream.java:71*)

  at org.drools.core.util.DroolsStreamUtils.streamIn(***DroolsStreamUtils.java:205*)

  at org.drools.core.util.DroolsStreamUtils.streamIn(***DroolsStreamUtils.java:174*)

  at org.drools.agent.impl.KnowledgeAgentImpl.createPackageFromResource(***KnowledgeAgentImpl.java:653*)

  ... 9 more

I’m running Drools 5.1.1 on my workstation in Eclipse.  When I run it against Guvnor locally using version 5.1.1 installed as the “Guvnor Standalone” downloaded at the same time as Drools 5.1.1 was downloaded from the JBoss.org site, it works fine.

When I run it against the server, which was from the 5.0.1 “Guvnor Standalone” installation, but I updated the drools-guvnor.war file to use the new 5.1.1 version, I get the error listed above.  Based on my research into the “KnowledgeAgent exception while trying to deserialize KnowledgeDefinitionsPackage” error, it seems to stem from an incompatibility between versions of Drools.

Do I need to install the 5.1.1 Guvnor Standalone to my server to bring the versions into synch, or am I experiencing some other sort of problem?