i recently upgrade JBossAS from 4.0.3 to 4.0.5GA. since i was already using JBossCache 2.0.0GA, which is newer than the one used by JBossAS, i had to upgrade the jboss-cache jar in the AS. The problem is that there's no backward compatability in jboss-cache & the 2.0.0 version can not be used together with Clusetered SSO. class org.jboss.web.tomcat.tc5.sso.ClusteredSingleSignOn which is required for clustered SSO has an import to class org.jboss.cache.AbstractTreeCacheListener which no longer exist in JBossCache. i would expect backward compatability. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4102904#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...