diff --git a/tempest/test.py b/tempest/test.py
index 75eb6be..d2568a6 100644
--- a/tempest/test.py
+++ b/tempest/test.py
@@ -510,6 +510,10 @@
             new_url, body = self._http_arguments(valid_schema, url, method)
         elif hasattr(self, "schema"):
             new_url, body = self._http_arguments(self.schema, url, method)
+        else:
+            raise Exception("testscenarios are not active. Please make sure "
+                            "that your test runner supports the load_tests "
+                            "mechanism")
 
         if "admin_client" in description and description["admin_client"]:
             client = self.admin_client