diff --git a/core/lib/Drupal/Core/Menu/LocalTaskManager.php b/core/lib/Drupal/Core/Menu/LocalTaskManager.php
index cfd91e1..b9c7895 100644
--- a/core/lib/Drupal/Core/Menu/LocalTaskManager.php
+++ b/core/lib/Drupal/Core/Menu/LocalTaskManager.php
@@ -274,7 +274,9 @@ public function getTasksBuild($current_route_name) {
             // The request is injected, so we need to verify that we have the
             // expected _raw_variables attribute.
             $raw_variables_bag = $this->request->attributes->get('_raw_variables');
-            $raw_variables = $raw_variables_bag ? $raw_variables_bag->all() : array();
+            // If we don't have _raw_variables, we assume the attributes are
+            // still the original values.
+            $raw_variables = $raw_variables_bag ? $raw_variables_bag->all() : $this->request->attributes->all();
             $active = array_intersect_assoc($route_parameters, $raw_variables) == $route_parameters;
           }
           // The plugin may have been set active in getLocalTasksForRoute() if