diff --git a/cdisc_rules_engine/services/data_services/usdm_data_service.py b/cdisc_rules_engine/services/data_services/usdm_data_service.py
index 3d603a1ed..675f72c02 100644
--- a/cdisc_rules_engine/services/data_services/usdm_data_service.py
+++ b/cdisc_rules_engine/services/data_services/usdm_data_service.py
@@ -455,6 +455,12 @@ def __get_datasets_content_index(self, dataset_name: str, json) -> List[dict]:
         dataset_dict = {}
         for path in metadata:
             entity = path["entity"]
+
+            if entity is None:
+                raise ValueError(
+                    f"Invalid metadata: 'entity' is null for path '{path.get('path')}'"
+                )
+
             if entity.lower() == "code":
                 entity = "Code"
             # Do not skip 'null' entities; include them as datasets