diff --git a/src/azure-cli-core/azure/cli/core/aaz/_content_builder.py b/src/azure-cli-core/azure/cli/core/aaz/_content_builder.py
index b51b6a7be9e..76ddab1ffa7 100644
--- a/src/azure-cli-core/azure/cli/core/aaz/_content_builder.py
+++ b/src/azure-cli-core/azure/cli/core/aaz/_content_builder.py
@@ -79,8 +79,9 @@ def set_prop(self, prop_name, typ, arg_key=None, typ_kwargs=None):
                             value[prop_name] = {}
                     else:
                         raise NotImplementedError()
-                sub_values.append(value[prop_name])
-                sub_args.append(sub_arg)
+                if value != None:
+                    sub_values.append(value[prop_name])
+                    sub_args.append(sub_arg)
 
         if sub_values:
             self._sub_prop_builders[prop_name] = AAZContentBuilder(sub_values, sub_args)