diff --git a/app/scodoc/sco_formation_versions.py b/app/scodoc/sco_formation_versions.py
index 9cce0c3a..e4a5937e 100644
--- a/app/scodoc/sco_formation_versions.py
+++ b/app/scodoc/sco_formation_versions.py
@@ -200,7 +200,7 @@ def do_formsemestres_associate_new_version(
 
     # New formation:
     (
-        formation_id,
+        new_formation_id,
         modules_old2new,
         ues_old2new,
     ) = sco_formations.formation_create_new_version(formation_id, redirect=False)
@@ -219,7 +219,7 @@ def do_formsemestres_associate_new_version(
     # re-associate
     for formsemestre_id in formsemestre_ids:
         formsemestre = FormSemestre.get_formsemestre(formsemestre_id)
-        formsemestre.formation_id = formation_id
+        formsemestre.formation_id = new_formation_id
         db.session.add(formsemestre)
         _reassociate_moduleimpls(formsemestre, ues_old2new, modules_old2new)
 
@@ -246,8 +246,12 @@ def _reassociate_moduleimpls(
         Evaluation.moduleimpl_id == ModuleImpl.id,
         ModuleImpl.formsemestre_id == formsemestre.id,
     ):
-        poids.ue_id = ues_old2new[poids.ue_id]
-        db.session.add(poids)
+        if poids.ue_id in ues_old2new:
+            poids.ue_id = ues_old2new[poids.ue_id]
+            db.session.add(poids)
+        else:
+            # poids vers une UE qui n'est pas ou plus dans notre formation
+            db.session.delete(poids)
 
     # update decisions:
     for event in ScolarEvent.query.filter_by(formsemestre_id=formsemestre.id):
@@ -258,8 +262,9 @@ def _reassociate_moduleimpls(
     for validation in ScolarFormSemestreValidation.query.filter_by(
         formsemestre_id=formsemestre.id
     ):
-        if validation.ue_id is not None:
+        if (validation.ue_id is not None) and validation.ue_id in ues_old2new:
             validation.ue_id = ues_old2new[validation.ue_id]
+            # si l'UE n'est pas ou plus dans notre formation, laisse.
         db.session.add(validation)
 
     db.session.commit()