diff --git a/addons/account/account_invoice.py b/addons/account/account_invoice.py
index e94a60a545c..e2eddf5b9b0 100644
--- a/addons/account/account_invoice.py
+++ b/addons/account/account_invoice.py
@@ -1261,7 +1261,7 @@ class account_invoice_line(models.Model):
uos_id = fields.Many2one('product.uom', string='Unit of Measure',
ondelete='set null', index=True)
product_id = fields.Many2one('product.product', string='Product',
- ondelete='set null', index=True)
+ ondelete='restrict', index=True)
account_id = fields.Many2one('account.account', string='Account',
required=True, domain=[('type', 'not in', ['view', 'closed'])],
default=_default_account,
diff --git a/addons/product/product_view.xml b/addons/product/product_view.xml
index c764ab06045..01c9ff2d721 100644
--- a/addons/product/product_view.xml
+++ b/addons/product/product_view.xml
@@ -250,6 +250,11 @@
+ Warning: adding or deleting attributes + will delete and recreate existing variants and lead + to the loss of its eventual customizations. +