Hi everyone, I am using "mapped-superclass" element in persistence XML and I am getting the following error message: "Reason: java.lang.ClassCastException: $Proxy169", while using @MappedSuperclass notation everything works fine. I must specify that the persistence provider I am working with is Hibernate and JBoss version 4.0.4. The following is the exact persistence XML: <?xml version="1.0" encoding="UTF-8"?> <entity-mappings xmlns="http://java.sun.com/xml/ns/persistence/orm" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/persistence/orm http://java.sun.com/xml/ns/persistence/orm_1_0.xsd" version="1.0"> <persistence-unit-metadata> <xml-mapping-metadata-complete/> </persistence-unit-metadata> <mapped-superclass class="com.fts.domain.ValueObject"/> <sequence-generator name="CUSTOMER_PK" sequence-name="CUSTOMER_SEQ"/> <generated-value generator="CUSTOMER_PK"/> </entity-mappings> I will appreciate any help. Thanks a lot Ilan View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=3967689#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...