diff --git a/core/modules/block/lib/Drupal/block/BlockListController.php b/core/modules/block/lib/Drupal/block/BlockListController.php
index 618b901..cafc1fd 100644
--- a/core/modules/block/lib/Drupal/block/BlockListController.php
+++ b/core/modules/block/lib/Drupal/block/BlockListController.php
@@ -326,7 +326,6 @@ public function buildForm(array $form, array &$form_state) {
         $form['right']['list'][$category] = array(
           '#type' => 'details',
           '#title' => $category,
-          '#collapsed' => TRUE,
           'content' => array(
             '#theme' => 'links',
             '#links' => array(),