I didn't know that there could be an error when I am trying to render a JSF application with JSP extension.
I was running my Tomcat server. With JSF servlet mapping like this:
Suppose I should enter this URL http:// localhost:8080 / web6 / sample.jsf, and change the JSF extension to JSP, this could turn Tomcat server throwing an exception javax.servlet.jsp.JspException: Cannot find FacesContext:
Full stack trace: