Remember NOT TO PACKAGE the portlet api into the war file! It will fail the deployment!

Problem description as follow:

17:21:51,982 ERROR [PortletWebApp] An error occured when the portlet started
org.jboss.portal.portlet.PortletInitializationException: The portlet … threw a runtime exception during init
at org.jboss.portal.portlet.PortletContainer.start(PortletContainer.java:228)
at org.jboss.portal.portlet.PortletWebApp.startService(PortletWebApp.java:100)
at org.jboss.system.ServiceMBeanSupport.jbossInternalStart(ServiceMBeanSupport.java:274)
at org.jboss.system.ServiceMBeanSupport.start(ServiceMBeanSupport.java:181)
at org.jboss.portal.common.system.AbstractJBossService.start(AbstractJBossService.java:73)
……….
at org.jboss.deployment.scanner.AbstractDeploymentScanner$ScannerThread.run(AbstractDeploymentScanner.java:182)
Caused by: java.lang.ClassCastException
at org.jboss.portal.portlet.PortletContainer.start(PortletContainer.java:194)
… 113 more