diff --git a/addons/purchase/models/purchase.py b/addons/purchase/models/purchase.py
index 16d82fe08da..1986112de45 100644
--- a/addons/purchase/models/purchase.py
+++ b/addons/purchase/models/purchase.py
@@ -346,8 +346,11 @@ class PurchaseOrder(models.Model):
             return groups
 
         self.ensure_one()
-        customer_portal_group = next(group for group in groups if group[0] == 'portal_customer')
-        if customer_portal_group:
+        try:
+            customer_portal_group = next(group for group in groups if group[0] == 'portal_customer')
+        except StopIteration:
+            pass
+        else:
             access_opt = customer_portal_group[2].setdefault('button_access', {})
             if self.env.context.get('is_reminder'):
                 access_opt['title'] = _('View')