diff --git a/lib/dl_core/dl_core/us_manager/storage_schemas/base_types.py b/lib/dl_core/dl_core/us_manager/storage_schemas/base_types.py
index 873eebefd..4cdfd9401 100644
--- a/lib/dl_core/dl_core/us_manager/storage_schemas/base_types.py
+++ b/lib/dl_core/dl_core/us_manager/storage_schemas/base_types.py
@@ -20,7 +20,7 @@
 class NativeTypeSchema(Schema):
     """(currently used for uploads / ProviderConnection)"""
 
-    conn_type = DynamicEnumField(ConnectionType, by_value=True)
+    conn_type = DynamicEnumField(ConnectionType, by_value=True, load_default=ConnectionType.unknown)
     name = fields.String()
 
     @post_load(pass_many=False)