;

Forgetting to put f:view around your jsf content leads to this rather cryptic error message (this is the root cause of a JasperException):

java.lang.NullPointerException
at javax.faces.component.UIComponentBase.encodeBegin(UIComponentBase.java:683)
at javax.faces.component.UIViewRoot.encodeBegin(UIViewRoot.java:324)
at javax.faces.webapp.UIComponentTag.encodeBegin(UIComponentTag.java:591)
at javax.faces.webapp.UIComponentTag.doStartTag(UIComponentTag.java:478)