diff --git a/app_tpl/includes/header.html b/app_tpl/includes/header.html
index 0a35488..17d3f7c 100644
--- a/app_tpl/includes/header.html
+++ b/app_tpl/includes/header.html
@@ -28,4 +28,9 @@ <h1><a href="index.html">The Book of OpenLayers3 <span class="text-muted">[Code
           })();
         </script>
     </div>
+
+    <div class="col-md-12 alert alert-warning text-center" role="alert">
+        <strong>IMPORTANT !!!</strong> All samples works with OpenLayers v3.4.0 and prior versions.
+        New 3.5.0 version introduces some <a href="https://github.com/openlayers/ol3/blob/master/changelog/upgrade-notes.md#v350">API changes</a> not backwards compatible.
+    </div>
 </div>
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