diff --git a/src/Controller/SaveTaskController.php b/src/Controller/SaveTaskController.php
index acab630e..1df4e9f1 100644
--- a/src/Controller/SaveTaskController.php
+++ b/src/Controller/SaveTaskController.php
@@ -66,6 +66,8 @@ public function handle(ServerRequestInterface $request): ResponseInterface
 
         if (!$form->validate($vars)) {
             $_REQUEST['actionID'] = 'task_form';
+            // Legacy task.php expects Horde globals (e.g. on task list reload).
+            $GLOBALS['registry'] = $this->registry;
             require NAG_BASE . '/task.php';
             exit;
         }
diff --git a/task.php b/task.php
index d4c45c72..50f9a8c9 100644
--- a/task.php
+++ b/task.php
@@ -68,6 +68,12 @@ function _delete($task_id, $tasklist_id)
 require_once __DIR__ . '/lib/Application.php';
 Horde_Registry::appInit('nag');
 
+global $injector, $nag_shares, $notification, $registry;
+if (!isset($registry)) {
+    $registry = $GLOBALS['registry']
+        ?? $injector->getInstance('Horde_Registry');
+}
+
 $vars = Horde_Variables::getDefaultVariables();
 
 /* Redirect to the task list if no action has been requested. */