Odoo 10.0 Invalid Constraint

I've asked this question on odoo.com here. I'm trying to replace a field in the product.template view with a field of my own. In the gui, click Sales/Sales/Products, select a prod

Solution 1:

you write wrong xpath it should be

<xpath expr="//field[@name='project_id']" position="before">
     <field name="project_templates"/>
</xpath>