Piero,
To resolve the problem, add or replace the following context parameter in the web.xml file and republish the project.
<context-param>
<param-name>javax.faces.PARTIAL_STATE_SAVING</param-name>
<param-value>false</param-value>
</context-param>
That is because you are using a default JSF implementation for WAS (myFaces) and you have developed in mojarra, so you need to set that in order to work with myFaces.
Saludos