Here is the exception. BTW, I am using jboss 5.1.0 GA | 11:14:03,522 ERROR [Ejb3Deployment] Exception while processing container metadata for EJB: MySessionBean in unit: My.ear | 11:14:03,523 ERROR [AbstractKernelController] Error installing to Real: name=vfszip:/opt/tools/jboss-5.1.0.GA/server/default/deploy/My.ear/ state=PreReal mode=Manual requiredState=Real | org.jboss.deployers.spi.DeploymentException: Error deploying My.ear: Exception while processing container metadata for EJB: MySessionBean in unit: My.ear | at org.jboss.ejb3.deployers.Ejb3Deployer.deploy(Ejb3Deployer.java:196) | at org.jboss.ejb3.deployers.Ejb3Deployer.deploy(Ejb3Deployer.java:99) | at org.jboss.deployers.vfs.spi.deployer.AbstractVFSRealDeployer.internalDeploy(AbstractVFSRealDeployer.java:45) | at org.jboss.deployers.spi.deployer.helpers.AbstractRealDeployer.deploy(AbstractRealDeployer.java:50) | at org.jboss.deployers.plugins.deployers.DeployerWrapper.deploy(DeployerWrapper.java:171) | at org.jboss.deployers.plugins.deployers.DeployersImpl.doDeploy(DeployersImpl.java:1439) | at org.jboss.deployers.plugins.deployers.DeployersImpl.doInstallParentFirst(DeployersImpl.java:1157) | at org.jboss.deployers.plugins.deployers.DeployersImpl.install(DeployersImpl.java:1098) | at org.jboss.dependency.plugins.AbstractControllerContext.install(AbstractControllerContext.java:348) | at org.jboss.dependency.plugins.AbstractController.install(AbstractController.java:1631) | at org.jboss.dependency.plugins.AbstractController.incrementState(AbstractController.java:934) | at org.jboss.dependency.plugins.AbstractController.resolveContexts(AbstractController.java:1082) | at org.jboss.dependency.plugins.AbstractController.resolveContexts(AbstractController.java:984) | at org.jboss.dependency.plugins.AbstractController.change(AbstractController.java:822) and further Caused by: java.lang.IllegalArgumentException: Can't find a persistence unit named 'null' in AbstractVFSDeploymentContext@359971180{vfszip:/opt/tools/jboss-5.1.0.GA/server/default/deploy/My.ear/} | at org.jboss.jpa.resolvers.BasePersistenceUnitDependencyResolver.resolvePersistenceUnitSupplier(BasePersistenceUnitDependencyResolver.java:107) | at org.jboss.ejb3.Ejb3Deployment.resolvePersistenceUnitSupplier(Ejb3Deployment.java:770) | at org.jboss.ejb3.EJBContainer.resolvePersistenceUnitSupplier(EJBContainer.java:1428) | at org.jboss.injection.PersistenceUnitHandler.addPUDependency(PersistenceUnitHandler.java:130) | ... 33 more | 11:14:03,529 WARN [HDScanner] Failed to process changes | org.jboss.deployers.client.spi.IncompleteDeploymentException: Summary of incomplete deployments (SEE PREVIOUS ERRORS FOR DETAILS): View the original post : http://www.jboss.org/index.html?module=bb&op=viewtopic&p=4249749#... Reply to the post : http://www.jboss.org/index.html?module=bb&op=posting&mode=reply&a...