Hello
This is my pivot view in odoo 10, when i want to extract it in xlsx file i get the error : "Uncaught SyntaxError: Unexpected token T in JSON at position 0" ?? How i can fix it ?

<record id="view_pivot_todo_task" model="ir.ui.view">
<field name="model">todo.task</field>
  <field name="arch" type="xml">
    <pivot>
      <field name="stage_id" type="col"/>
      <field name="user_id"/>
      <field name="date_deadline" interval="week"/>
      <field name="effort_estimate" type="measure"/>
    </pivot>
  </field>
</record>

Odoo Error
Uncaught SyntaxError: Unexpected token T in JSON at position 0   http://localhost:8069/web#view_type=pivot&model=mrp.trs&menu_id=392&action=543:1
    Retraçage :
    SyntaxError: Unexpected token T in JSON at position 0
        at JSON.parse (<anonymous>)
        at HTMLIFrameElement.<anonymous> (http://localhost:8069/web/content/988-e553e62/web.assets_common.js:3043:379)
        at HTMLIFrameElement.dispatch (http://localhost:8069/web/content/988-e553e62/web.assets_common.js:637:451)
        at HTMLIFrameElement.elemData.handle (http://localhost:8069/web/content/988-e553e62/web.assets_common.js:610:173)