When i try to create an invoice from a sales order, i get this error. I checked my custom modules but none of them do anything to the product.product model. 
All i do is set a value for company_id when creating a new product.template record. I also did not change any user or group access right.

Why does this error occur? Could there be any issue with product.template that is causing Odoo to restrict user access to product.product?

If you have any ideas to solve this, please let me know.

Thanks a lot.

Due to security restrictions, you are not allowed to access 'Product Variant' (product.product) records.

Records: Down payment (id=246)
User: Administrator (id=2)

This restriction is due to the following rules:


Contact your administrator to request access if necessary.

Implicitly accessed through 'Product Variant' (product.product).