Restart Odoo and upgrade your module after changes.

Hope it helps

Here’s the corrected and clarified XML code for adding a new field using an xpath expression while inheriting from product.product_normal_form_view:

<odoo>

    <record id="product_variant_custom_form_view" model="ir.ui.view">

        <field name="name">product.product.form.custom</field>

        <field name="model">product.product</field>

        <field name="inherit_id" ref="product.product_normal_form_view"/>

        <field name="arch" type="xml">

            <!-- Add the new field after the 'existing_field' field  -->

            <xpath expr="//field[@name='existing_field']" position="after">

                <field name="new_field_name"/>

            </xpath>

        </field>

    </record>

</odoo>

Regards,

Jishna

Accurates

thank you i use this code but it not add any thing and no errors ???

The product.product model shares most views with product.template, but has its own specific form view product.product_normal_form_view. Here's how to inherit it:

<odoo>

    <record id="product_variant_custom_form_view" model="ir.ui.view">

        <field name="name">product.product.form.custom</field>

        <field name="model">product.product</field>

        <field name="inherit_id" ref="product.product_normal_form_view"/>

        <field name="arch" type="xml">

            <!-- Add your custom fields/modifications here -->

        </field>

    </record>

</odoo>