JBoss 7 - Caused by: org.dom4j.DocumentException: org.dom4j.DocumentFactory cannot be cast to org.dom4j.DocumentFactory Nested exception: org.dom4j.DocumentFactory cannot be cast to org.dom4j.DocumentFactory

Simple solution to fix this issue:

https://docs.jboss.org/author/display/AS7/Class+Loading+in+AS7

If you do not want to read the above URL, which is really not giving the straight forward solution:

1 - Open {your war}/META-INF/MANIFEST.MF

2 - Add this line at the end - Dependencies: org.dom4j export

You do not need to do any of the following:

1 - jboss-deployment-structure.xml - exclussions

2 - Adding subsystem to include org.dom4j as global modules

3 - Remove your dom4j-1.6.1.jar from your WEB-INF/lib directory

Most of the time you hit this problem when you try to deploy a war that has hibernate 4 included in it. In this case you may want to do the following for JBoss 7:

To your persistence.xml add the following properties, which is not need for tomcat (assuming you are using oracle > 10g).

 <properties >
    <property name="hibernate.dialect" value="org.hibernate.dialect.Oracle10gDialect"/ >
    <property name="hibernate.listeners.envers.autoRegister" value="false"/ >
</properties >