When deploying an application in Weblogic you can come across a Hibernate CoreMessageLogger NoClassDefFoundError on Weblogic:

Caused By: java.lang.NoClassDefFoundError: org/hibernate/internal/CoreMessageLogger
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClassCond(ClassLoader.java:631)
at java.lang.ClassLoader.defineClass(ClassLoader.java:615)
at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:141)
at weblogic.utils.classloaders.GenericClassLoader.defineClass(GenericClassLoader.java:342)
at weblogic.utils.classloaders.GenericClassLoader.findLocalClass(GenericClassLoader.java:301)
at weblogic.utils.classloaders.GenericClassLoader.findClass(GenericClassLoader.java:269)
at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
at java.lang.ClassLoader.loadClass(ClassLoader.java:247)
at weblogic.utils.classloaders.GenericClassLoader.loadClass(GenericClassLoader.java:178)
at org.hibernate.ejb.Ejb3Configuration.(Ejb3Configuration.java:142)
at org.hibernate.ejb.HibernatePersistence.createContainerEntityManagerFactory(HibernatePersistence.java:72)
at weblogic.persistence.BasePersistenceUnitInfo.initializeEntityManagerFactory(BasePersistenceUnitInfo.java:446)
at weblogic.persistence.BasePersistenceUnitInfo.initializeEntityManagerFactory(BasePersistenceUnitInfo.java:439)
at weblogic.persistence.BasePersistenceUnitInfo.init(BasePersistenceUnitInfo.java:117)
at weblogic.persistence.BaseJPAIntegrationProvider.createPersistenceUnitInfo(BaseJPAIntegrationProvider.java:53)
at weblogic.persistence.AbstractPersistenceUnitRegistry.storeDescriptors(AbstractPersistenceUnitRegistry.java:404)
at weblogic.persistence.EarPersistenceUnitRegistry.initialize(EarPersistenceUnitRegistry.java:72)
at weblogic.persistence.PersistenceDeployment$PersistenceDeploymentExtension.prepare(PersistenceDeployment.java:81)
at weblogic.application.internal.flow.AppDeploymentExtensionFlow.prepare(AppDeploymentExtensionFlow.java:23)
at weblogic.application.internal.BaseDeployment$1.next(BaseDeployment.java:706)
at weblogic.application.utils.StateMachineDriver.nextState(StateMachineDriver.java:35)
at weblogic.application.internal.BaseDeployment.prepare(BaseDeployment.java:237)
at weblogic.application.internal.EarDeployment.prepare(EarDeployment.java:61)
at weblogic.application.internal.DeploymentStateChecker.prepare(DeploymentStateChecker.java:158)
at weblogic.deploy.internal.targetserver.AppContainerInvoker.prepare(AppContainerInvoker.java:60)
at weblogic.deploy.internal.targetserver.operations.ActivateOperation.createAndPrepareContainer(ActivateOperation.java:207)
at weblogic.deploy.internal.targetserver.operations.ActivateOperation.doPrepare(ActivateOperation.java:96)
at weblogic.deploy.internal.targetserver.operations.AbstractOperation.prepare(AbstractOperation.java:229)
at weblogic.deploy.internal.targetserver.DeploymentManager.handleDeploymentPrepare(DeploymentManager.java:747)
at weblogic.deploy.internal.targetserver.DeploymentManager.prepareDeploymentList(DeploymentManager.java:1216)
at weblogic.deploy.internal.targetserver.DeploymentManager.handlePrepare(DeploymentManager.java:250)
at weblogic.deploy.internal.targetserver.DeploymentServiceDispatcher.prepare(DeploymentServiceDispatcher.java:159)
at weblogic.deploy.service.internal.targetserver.DeploymentReceiverCallbackDeliverer.doPrepareCallback(DeploymentReceiverCallbackDeliverer.java:171)
at weblogic.deploy.service.internal.targetserver.DeploymentReceiverCallbackDeliverer.access$000(DeploymentReceiverCallbackDeliverer.java:13)
at weblogic.deploy.service.internal.targetserver.DeploymentReceiverCallbackDeliverer$1.run(DeploymentReceiverCallbackDeliverer.java:46)
at weblogic.work.SelfTuningWorkManagerImpl$WorkAdapterImpl.run(SelfTuningWorkManagerImpl.java:545)
at weblogic.work.ExecuteThread.execute(ExecuteThread.java:256)
at weblogic.work.ExecuteThread.run(ExecuteThread.java:221)

Solving CoreMessageLogger NoClassDefFoundError

This problem can occur when you have a Hibernate 3.x and a Hibernate 4.x dependency in your classpath, and the Hibernate 3 dependency was first on your classpath.

Look in your Maven Dependency hierarchy to see where the Hibernate 3 / 4 dependencies come from and solve it by eg. excluding transitive dependencies in your POM.