diff --git a/core/Plugin/Manager.php b/core/Plugin/Manager.php
index cf7cc09baed435ff65dbe21c37f85789a812dfdc..b7a397b587ef1b7f390193c5093e52df943744fe 100644
--- a/core/Plugin/Manager.php
+++ b/core/Plugin/Manager.php
@@ -65,6 +65,7 @@ class Manager
     // These are always activated and cannot be deactivated
     protected $pluginToAlwaysActivate = array(
         'CoreHome',
+        'Diagnostics',
         'CoreUpdater',
         'CoreAdminHome',
         'CoreConsole',