While working on
MYFACES-2614 I ran into the problem that, if a conversion fails, the error page is displayed with the related ConverterException. This should not happen, instead a FacesMessage describing the conversion error should be added to the FacesContext.
See section 2.2.3 Process Validations (or also section 2.2.2. Apply Request Values for components with immediate set to true) of the JSF 2.0 spec: "Conversions and Validations that failed will have caused messages to be enqueued via calls to addMessage()...".