diff --git a/CHANGES.rst b/CHANGES.rst
index 3605c138..3d4c2997 100644
--- a/CHANGES.rst
+++ b/CHANGES.rst
@@ -5,8 +5,8 @@ Changelog
 5.1.16 (unreleased)
 -------------------
 
-- Nothing changed yet.
-
+- Return Bando.apertura_bando as null if had been set default("1100-01-01T00:00:00").
+  [folix-01]
 
 5.1.15 (2024-09-16)
 -------------------
diff --git a/src/design/plone/contenttypes/restapi/serializers/summary.py b/src/design/plone/contenttypes/restapi/serializers/summary.py
index 4d326f6b..bb5a1e94 100644
--- a/src/design/plone/contenttypes/restapi/serializers/summary.py
+++ b/src/design/plone/contenttypes/restapi/serializers/summary.py
@@ -27,6 +27,14 @@ def __call__(self, force_all_metadata=False):
             if "bando_state" in metadata_fields or self.show_all_metadata_fields:
                 res["bando_state"] = self.get_bando_state()
 
+            # if default set to None
+            if (
+                "apertura_bando" in metadata_fields
+                or self.show_all_metadata_fields
+                and res["apertura_bando"] == "1100-01-01T00:00:00"
+            ):
+                res["apertura_bando"] = None
+
         if "geolocation" in metadata_fields or self.show_all_metadata_fields:
             # backward compatibility for some block templates
             if "geolocation" not in res: