diff --git a/models/sale_project.py b/models/sale_project.py
index bfde5b16aeb2fd090c6a5b6038c4f9a783229501..f7a993374b96affb480fff471193afef39fc5964 100644
--- a/models/sale_project.py
+++ b/models/sale_project.py
@@ -96,7 +96,10 @@ class SaleProject(models.Model):
     )
 
     saison_id = fields.Many2one(
-        "sale.project.saison", "Saison", default=_get_default_saison_id
+        "sale.project.saison",
+        "Saison",
+        default=_get_default_saison_id,
+        ondelete="restrict",
     )
     date_visit = fields.Date("Date de visite")
 
@@ -157,9 +160,11 @@ class SaleProject(models.Model):
         for rec in res:
             rec.geo_sector_id = rec.sale_order_id.partner_id.geo_sector_id.id
             seq = str(rec.sale_order_id.partner_id.sale_project_count).zfill(3)
-            rec.name = (
-                rec.sale_order_id.partner_id.ref + "-" + rec.saison_id.name + "-" + seq
-            )
+            if rec.saison_id:
+                saison_name = "-" + rec.saison_id.name
+            else:
+                saison_name = ""
+            rec.name = rec.sale_order_id.partner_id.ref + saison_name + "-" + seq
 
     def unlink(self):
         self.sale_order_line_ids.unlink()