diff -u b/core/modules/field_ui/lib/Drupal/field_ui/FieldOverview.php b/core/modules/field_ui/lib/Drupal/field_ui/FieldOverview.php
--- b/core/modules/field_ui/lib/Drupal/field_ui/FieldOverview.php
+++ b/core/modules/field_ui/lib/Drupal/field_ui/FieldOverview.php
@@ -101,7 +101,7 @@
           '#type' => 'textfield',
           '#title' => t('Weight for @title', array('@title' => $instance['label'])),
           '#title_display' => 'invisible',
-          '#default_value' => $widget_configuration['weight'],
+          '#default_value' => $widget_configuration ? $widget_configuration['weight'] : '0',
           '#size' => 3,
           '#attributes' => array('class' => array('field-weight')),
          ),
@@ -132,7 +132,7 @@
         ),
         'widget_type' => array(
           '#type' => 'link',
-          '#title' => $widget_types[$widget_configuration['type']]['label'],
+          '#title' => $widget_configuration ? $widget_types[$widget_configuration['type']]['label'] : $widget_types['hiden']['label'],
           '#href' => $admin_field_path . '/widget-type',
           '#options' => array('attributes' => array('title' => t('Change widget type.'))),
         ),
diff -u b/core/modules/field_ui/lib/Drupal/field_ui/Tests/ManageFieldsTest.php b/core/modules/field_ui/lib/Drupal/field_ui/Tests/ManageFieldsTest.php
--- b/core/modules/field_ui/lib/Drupal/field_ui/Tests/ManageFieldsTest.php
+++ b/core/modules/field_ui/lib/Drupal/field_ui/Tests/ManageFieldsTest.php
@@ -373,10 +373,12 @@
       'field_uuid' => $field->uuid,
       'entity_type' => 'node',
       'bundle' => $this->type,
-      'widget' => array(
-        'type' => 'test_field_widget',
-      )
     ))->save();
+    entity_get_form_display('node', $this->type, 'default')
+      ->setComponent($field->id, array(
+        'type' => 'test_field_widget',
+      ))
+      ->save();
 
     // Check that the links for edit and delete are not present.
     $this->drupalGet('admin/structure/types/manage/' . $this->type . '/fields');