diff --git a/app/views/notes.py b/app/views/notes.py
index 0572353b..1201747e 100644
--- a/app/views/notes.py
+++ b/app/views/notes.py
@@ -3106,7 +3106,10 @@ def formsemestre_set_elt_sem_apo():
     """Change les codes étapes du semestre indiqué.
     Args: oid=formsemestre_id, value=chaine "V3ONM, V3ONM1, V3ONM2", codes séparés par des virgules
     """
-    oid = int(request.form.get("oid"))
+    try:
+        oid = int(request.form.get("oid"))
+    except (TypeError, ValueError) as exc:
+        raise ScoValueError("paramètre invalide") from exc
     value = (request.form.get("value") or "").strip()
     formsemestre: FormSemestre = FormSemestre.query.get_or_404(oid)
     if value != formsemestre.elt_sem_apo: