diff --git a/osm_nbi/instance_topics.py b/osm_nbi/instance_topics.py
index 3eb14d2..607dc73 100644
--- a/osm_nbi/instance_topics.py
+++ b/osm_nbi/instance_topics.py
@@ -377,7 +377,7 @@
             elif ns_request.get("vnf"):
                 vnf_data = ns_request.get("vnf")
                 for vnf in vnf_data:
-                    for vdu in vnf.get("vdu"):
+                    for vdu in vnf.get("vdu", []):
                         if vdu.get("vim-flavor-name") and vdu.get("vim-flavor-id"):
                             raise EngineException(
                                 "Instantiation parameters vim-flavor-name and vim-flavor-id are mutually exclusive"