Activate multi-company, deactivate the common contact book. Create a PO P with user U1 in company A. Switch to company B. User U2 in company A tries to send P by email. Rendering of the template fails, because it tries to access object.create_uid, which breaks multi-company record rules. The signature was not working because it used user_id, a non-existing field, instead of create_uid. opw 1930521 closes odoo/odoo#30868