A Request fail dialog show when using ajax form with date widget has converter variant="datetime"

[lingerer]

Hi
    To repeat this error ,you can modify the sample.Under
build\webapp\samples\blocks\forms\forms\form1_template.xml
    1.Change <ft:form-template action="#{$cocoon/continuation/id}.continue"
method="POST">  to <ft:form-template
action="#{$cocoon/continuation/id}.continue" method="POST" ajax="true">
   2.Delete all repeater display to avoid the repeater error under ajax mode

   Now ,you can just open
http://localhost:8888/samples/blocks/forms/form1.flow click submit,then a