What version of Seam are you using? Have you tried with 2.0.0.CR1? I looked around for the usages of Manage.currentConversationIdStack and I don't think an UnmodifiableList is assigned anywhere. Do you make any modifications of values related to conversations? anonymous wrote : I also assigned a different conversation id with its begin method. What do you mean by this? Can you post your code? View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4086451#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...