diff --git a/app/scodoc/sco_permissions_check.py b/app/scodoc/sco_permissions_check.py
index 5c166dbe..fe21b167 100644
--- a/app/scodoc/sco_permissions_check.py
+++ b/app/scodoc/sco_permissions_check.py
@@ -168,7 +168,7 @@ def can_change_groups(formsemestre_id):
     "Vrai si l'utilisateur peut changer les groupes dans ce semestre"
     from app.scodoc import sco_formsemestre
 
-    sem = sco_formsemestre.get_formsemestre(formsemestre_id)
+    sem = sco_formsemestre.get_formsemestre(formsemestre_id, raise_soft_exc=True)
     if not sem["etat"]:
         return False  # semestre verrouillé
     if current_user.has_permission(Permission.ScoEtudChangeGroups):