I've never tried to deploy an Errai app in WebSphere, but I can offer these two questions/hints that might help:
1. Do you have the empty WEB-INF/beans.xml file in your deployment, and a META-INF/beans.xml in each jar that contains CDI beans?
2. Does the exact same app work when deployed to JBoss AS 7?
Hi Peter, currently the server-side integration of Errai CDI is not a fully portable extension and relies on Weld-specific features. It thus works fine with JBoss AS and GlassFish. The reason for this is principally that te CDI 1.0 specification was missing some things that were needed to facilitate our itnegration. These issues have been ameliorated in CDI 1.1, so we expect that our CDI Extension will be more portable across appservers in the future.