I don't think whether the attachment signature is Serializable matters. Other contexts require attachments to be Serializable so I would not change it. Just marking the attachment field as transient does what is needed. I was thinking there was an attachment being written in the ManagedPropertyImpl, but I guess I already removed that from the DefaultFieldsImpl.writeObject. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4122702#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...