ADF ADFC-12001 ControllerException pop last entry from page flow scope stack

I was getting the following error in my logs when closing a popup (everything worked though) :

Caused by: oracle.adf.controller.ControllerException: ADFC-12001: The ADF Controller is attempting to pop last entry from page flow scope stack.

I had to call my popup page directley instead of using a task flow to a resolve this.

Launch popup button:

<af:commandLink text="#{viewBundle.ABOUT_HELPABOUT_TITLE}"
  id="pt_cl21" inlineStyle="color: white; white-space: nowrap; "
  action="dialog:helpAbout" useWindow="true" windowWidth="480" windowHeight="340"
  clientComponent="true" immediate="true" windowEmbedStyle="inlineDocument"
  windowModalityType="applicationModal"/>

Entry in adfc config:

  <view id="helpAbout">
   <page>/pages/help/about.jspx</page>
  </view>
  <control-flow-rule id="__8">
    <from-activity-id>*</from-activity-id>
    <control-flow-case id="__9">     
  <from-outcome>dialog:helpAbout</from-outcome>
      <to-activity-id>helpAbout</to-activity-id>
    </control-flow-case>
  </control-flow-rule>

In my popup the clode button just calls this method :

  public String doClose() throws IOException {
    AdfFacesContext.getCurrentInstance().returnFromDialog(null, null);
    return null;
  }