@Raoul: In our project we are also using Richfaces and Trinidad together. I encountered exactly the same problem. I created a jira issue for that: http://jira.jboss.org/jira/browse/JBSEAM-2374 Well, until now I have found no solution to the problem and just live with the error message in the log.. but you are right, that is not an applicable solution. Even worse since the Richfaces version prior 3.1.3 show the error *every* time the page is loading, not only the first. And I have to use Richfaces 3.1.2 because later versions have a still unsolved memory leak with the dropdown menue in Firefox. Well, all in all Richfaces work together with Trinidad however, there are small but nasty issues when using them together... one thing for example is the different approach of partial page rendering.. And the use of Trinidad tables (tr:table is much better than Richfaces tables imho and this is the main reason why we are using Trinidad) with Richfaces a4jsf controls can also be a bit tricky sometimes... Please let me know if you find a solution... or encounter other problems.. maybe I could help.. Regards, Alexander View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4125292#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...