Fluid

This viewhelper seems to look for errors in
$errors = $this->controllerContext->getRequest()->getErrors();
which seems not filled if rewrittenPropertyMapper is enabled

Compare:
//nothing shown:
<f:form.errors>

<li>{error.code}: {error.message}</li>
       </f:form.errors>

//works fine but is ugly:
<f:form.validationResults>
<f:for each="{validationResults.flattenedErrors}" as="fieldErrors">
<f:for each="{fieldErrors}" as="error">
<li>{error.code}: {error.message}</li>
</f:for>
</f:for>
</f:form.validationResults>