diff --git a/multi_user/bl_types/bl_object.py b/multi_user/bl_types/bl_object.py
index 2d8304e..281cd08 100644
--- a/multi_user/bl_types/bl_object.py
+++ b/multi_user/bl_types/bl_object.py
@@ -135,6 +135,10 @@ class BlObject(BlDatablock):
             data_uuid,
             find_data_from_name(data_id),
             ignore=['images'])  # TODO: use resolve_from_id
+
+        if object_data is None and data_uuid:
+            raise Exception(f"Fail to load object {data['name']}({self.uuid})")
+
         instance = bpy.data.objects.new(object_name, object_data)
         instance.uuid = self.uuid
 
diff --git a/multi_user/operators.py b/multi_user/operators.py
index c3ff65b..aa5d171 100644
--- a/multi_user/operators.py
+++ b/multi_user/operators.py
@@ -78,19 +78,23 @@ def initialize_session():
     settings = utils.get_preferences()
     runtime_settings = bpy.context.window_manager.session
 
-    logging.info("Constructing nodes")
     # Step 1: Constrect nodes
+    logging.info("Constructing nodes")
     for node in session._graph.list_ordered():
         node_ref = session.get(uuid=node)
-        if node_ref.state == FETCHED:
+        if node_ref and node_ref.state == FETCHED:
             node_ref.resolve()
-
-    logging.info("Loading nodes")
+        else:
+            logging.error(f"Can't construct node {node}")
+    
     # Step 2: Load nodes
+    logging.info("Loading nodes")
     for node in session._graph.list_ordered():
         node_ref = session.get(uuid=node)
-        if node_ref.state == FETCHED:
+        if node_ref and node_ref.state == FETCHED:
             node_ref.apply()
+        else:
+            logging.error(f"Can't load node {node}")
 
     logging.info("Registering timers")
     # Step 4: Register blender timers