I am getting the following error when deploying a portlet in jboss portal server.
Caused by: java.lang.ClassCastException: com.xxx.JbossBirtPortlet cannot be cast to javax.portlet.Portlet
Figured out that including the portal core jar files in the web archive(war) creates this issue. Once I removed those jar files from the archive it started working. Because of classloader conflict the exception thrown at deploy time as jboss itself has its own portal jars and loaded when started.