diff --git a/models/sale.py b/models/sale.py
index b73c965e6d72b73e68c60f0a4cf6b8afc8717739..f83f498f3de1c97ae076f636abd79d6f19da6da7 100644
--- a/models/sale.py
+++ b/models/sale.py
@@ -53,7 +53,9 @@ class SaleOrder(models.Model):
         values = super()._prepare_invoice()
         values.update(
             {
-                "user_second_ids": fields.Command.create(self.user_second_ids.ids),
+                "user_second_ids": fields.Command.create(self.user_second_ids.ids)
+                if self.user_second_ids
+                else False,
                 "user_provider_id": self.user_provider_id.id or False,
             }
         )