diff --git a/developer_manual/app/appframework/tutorial.rst b/developer_manual/app/appframework/tutorial.rst
index 1d15d8a7c..28661e92e 100644
--- a/developer_manual/app/appframework/tutorial.rst
+++ b/developer_manual/app/appframework/tutorial.rst
@@ -15,6 +15,8 @@ Create an navigation entry
 --------------------------
 The **app.php** will always loaded for every app and can for instance be used to load additional JavaScript for the files app. Therefore the navigation entry has to be registered in this file.
 
+.. note:: The icon **img/example.png** needs to exist or the navigation will throw an error
+
 :file:`appinfo/app.php`
 
 .. code-block:: php