 <p>I think it is due to a jar conflict or maybe some jars are missing. Maybe you are using some other jars (in your application) apart of the ones you have included within your glassfish. Try to run a simple Fusion Web App (ex: only one jsf in it) and see if it runs. If it doesn't work then you might consider trying another Glassfish or to reconfigure it. I am using Glassfish 3.1.2.2 without problems.</p>