diff --git a/app/scodoc/sco_cache.py b/app/scodoc/sco_cache.py
index 0798a37d24..65307d7e96 100644
--- a/app/scodoc/sco_cache.py
+++ b/app/scodoc/sco_cache.py
@@ -231,29 +231,29 @@ def invalidate_formsemestre(  # was inval_cache(formsemestre_id=None, pdfonly=Fa
     """expire cache pour un semestre (ou tous si formsemestre_id non spécifié).
     Si pdfonly, n'expire que les bulletins pdf cachés.
     """
+    from app.models.formsemestre import FormSemestre
     from app.scodoc import sco_cursus
 
-    if getattr(g, "defer_cache_invalidation", False):
+    assert isinstance(formsemestre_id, int) or formsemestre_id is None
+    if getattr(g, "defer_cache_invalidation", 0) > 0:
         g.sem_to_invalidate.add(formsemestre_id)
         return
-    log(f"inval_cache, formsemestre_id={formsemestre_id} pdfonly={pdfonly}")
     if formsemestre_id is None:
         # clear all caches
-        log("----- invalidate_formsemestre: clearing all caches -----")
+        log(
+            f"----- invalidate_formsemestre: clearing all caches. pdfonly={pdfonly}-----"
+        )
         formsemestre_ids = [
-            x[0]
-            for x in ndb.SimpleQuery(
-                """SELECT id FROM notes_formsemestre s
-                WHERE s.dept_id=%(dept_id)s
-            """,
-                {"dept_id": g.scodoc_dept_id},
-            )
+            formsemestre.id
+            for formsemestre in FormSemestre.query.filter_by(dept_id=g.scodoc_dept_id)
         ]
     else:
         formsemestre_ids = [
             formsemestre_id
         ] + sco_cursus.list_formsemestre_utilisateurs_uecap(formsemestre_id)
-        log(f"----- invalidate_formsemestre: clearing {formsemestre_ids} -----")
+        log(
+            f"----- invalidate_formsemestre: clearing {formsemestre_ids}. pdfonly={pdfonly} -----"
+        )
 
     if not pdfonly:
         # Delete cached notes and evaluations
@@ -289,17 +289,19 @@ class DeferredSemCacheManager:
     """
 
     def __enter__(self):
-        assert not hasattr(g, "defer_cache_invalidation")
-        g.defer_cache_invalidation = True
-        g.sem_to_invalidate = set()
+        if not hasattr(g, "defer_cache_invalidation"):
+            g.defer_cache_invalidation = 0
+            g.sem_to_invalidate = set()
+        g.defer_cache_invalidation += 1
         return True
 
     def __exit__(self, exc_type, exc_value, exc_traceback):
         assert g.defer_cache_invalidation
-        g.defer_cache_invalidation = False
-        while g.sem_to_invalidate:
-            formsemestre_id = g.sem_to_invalidate.pop()
-            invalidate_formsemestre(formsemestre_id)
+        g.defer_cache_invalidation -= 1
+        if g.defer_cache_invalidation == 0:
+            while g.sem_to_invalidate:
+                formsemestre_id = g.sem_to_invalidate.pop()
+                invalidate_formsemestre(formsemestre_id)
 
 
 # ---- Nouvelles classes ScoDoc 9.2