diff --git a/app/scodoc/sco_formsemestre.py b/app/scodoc/sco_formsemestre.py
index 66953733..437969eb 100644
--- a/app/scodoc/sco_formsemestre.py
+++ b/app/scodoc/sco_formsemestre.py
@@ -297,10 +297,11 @@ def read_formsemestre_responsables(formsemestre_id: int) -> list[int]:  # py3.9+
 
 
 def _write_formsemestre_responsables(sem):  # TODO old, à ré-écrire avec models
-    sem["responsables"] = [
-        uid for uid in sem["responsables"] if (uid is not None) and (uid != -1)
-    ]
-    return _write_formsemestre_aux(sem, "responsables", "responsable_id")
+    if sem and "responsables" in sem:
+        sem["responsables"] = [
+            uid for uid in sem["responsables"] if (uid is not None) and (uid != -1)
+        ]
+        _write_formsemestre_aux(sem, "responsables", "responsable_id")
 
 
 # ----------------------  Coefs des UE