[TYPO3-mvc] Error: The key "Tx_Fluid_ViewHelpers_FormViewHelper->formFieldNames" was already stored and you cannot override it

[Albert van der Veen]

Hi all,

I'm trying to get a simple form into a Fluid template (typo3 4.5.19) and 
get the following error when calling the page in the frontend:

The key "Tx_Fluid_ViewHelpers_FormViewHelper->formFieldNames" was 
already stored and you cannot override it.

This is teh form part in the template:

<f:form action="question" name="question_form" id="question_form">
	<p>Question: <f:form.textfield name="info[question]" /></p>
	<p>Name: <f:form.textfield name="info[lastname]" /></p>
	<p>Email: <f:form.textfield name="info[email]" /></p>
</f:form>

Googling returns two results but no clues. Anyone?

Best,
Albert