diff --git a/core/modules/field/lib/Drupal/field/FieldInstance.php b/core/modules/field/lib/Drupal/field/FieldInstance.php
index bf0656e..75040c0 100644
--- a/core/modules/field/lib/Drupal/field/FieldInstance.php
+++ b/core/modules/field/lib/Drupal/field/FieldInstance.php
@@ -39,31 +39,15 @@ public function __construct(array $definition) {
   /**
    * Returns the Widget plugin for the instance.
    *
-   * @param bool $allow_hidden
-   *   (optional) Whether we are allowed to return the 'field_hidden' widget.
-   *   Defaults to TRUE.
+   * @param bool $skip_cache
+   *   (optional) Whether to skiup the static cache. Defaults to FALSE.
    *
    * @return \Drupal\field\Plugin\Type\Widget\WidgetInterface
    *   The Widget plugin to be used for the instance.
    */
-  public function getWidget($allow_hidden = TRUE) {
-    // Skip the static cache if we are getting the widget for the field instance
-    // settings form.
-    if (empty($this->widget) || !$allow_hidden) {
-      if (!$allow_hidden && $this->definition['widget']['type'] == 'field_hidden') {
-        $field = field_info_field_by_id($this->definition['field_id']);
-        $field_type = field_info_field_types($field['type']);
-        $default_widget = field_info_widget_types($field_type['default_widget']);
-
-        $widget_properties = array(
-          'type' => $default_widget['id'],
-          'settings' => $default_widget['settings'],
-          'weight' => 0,
-        );
-      }
-      else {
-        $widget_properties = $this->definition['widget'];
-      }
+  public function getWidget($skip_cache = FALSE) {
+    if (empty($this->widget) || $skip_cache) {
+      $widget_properties = $this->definition['widget'];
 
       // Let modules alter the widget properties.
       $context = array(
diff --git a/core/modules/field/lib/Drupal/field/Plugin/Type/LegacyDiscoveryDecorator.php b/core/modules/field/lib/Drupal/field/Plugin/Type/LegacyDiscoveryDecorator.php
index 6271209..1f94d7c 100644
--- a/core/modules/field/lib/Drupal/field/Plugin/Type/LegacyDiscoveryDecorator.php
+++ b/core/modules/field/lib/Drupal/field/Plugin/Type/LegacyDiscoveryDecorator.php
@@ -67,9 +67,8 @@ public function getDefinitions() {
           unset($definition['behaviors']['default value']);
         }
 
-        if (!isset($definition['id'])) {
-          $definition['id'] = $plugin_id;
-        }
+        // Legacy widgets also need a plugin id.
+        $definition['id'] = $plugin_id;
 
         $definitions[$plugin_id] = $definition;
       }
diff --git a/core/modules/field/lib/Drupal/field/Tests/FormTest.php b/core/modules/field/lib/Drupal/field/Tests/FormTest.php
index 5565699..eeb4ae0 100644
--- a/core/modules/field/lib/Drupal/field/Tests/FormTest.php
+++ b/core/modules/field/lib/Drupal/field/Tests/FormTest.php
@@ -591,10 +591,11 @@ function testFieldFormHiddenWidget() {
     field_create_instance($this->instance);
     $langcode = LANGUAGE_NOT_SPECIFIED;
 
-    // Display creation form.
+    // Display the entity creation form.
     $this->drupalGet('test-entity/add/test_bundle');
 
-    // Create an entity.
+    // Create an entity and test that the default value is assigned correctly to
+    // the field that uses the hidden widget.
     $this->assertNoField("{$this->field_name}[$langcode][0][value]", 'The hidden widget is not displayed');
     $this->drupalPost(NULL, array(), t('Save'));
     preg_match('|test-entity/manage/(\d+)/edit|', $this->url, $match);
diff --git a/core/modules/field_ui/field_ui.admin.inc b/core/modules/field_ui/field_ui.admin.inc
index 149c38e..7c779fb 100644
--- a/core/modules/field_ui/field_ui.admin.inc
+++ b/core/modules/field_ui/field_ui.admin.inc
@@ -692,7 +692,7 @@ function field_ui_widget_type_form_submit($form, &$form_state) {
     field_update_instance($instance);
     drupal_set_message(t('Changed the widget for field %label.', array('%label' => $instance['label'])));
 
-    if ($instance['required'] && empty($instance['default_value']) && $instance['widget']['type'] == 'field_hidden') {
+    if ($instance['required'] && empty($instance['default_value']) && empty($instance['default_value_function']) && $instance['widget']['type'] == 'field_hidden') {
       drupal_set_message(t('Field %label is required and uses the "hidden" widget. You might want to configure a default value.', array('%label' => $instance['label'])), 'warning');
     }
   }
@@ -938,10 +938,20 @@ function field_ui_default_value_widget($field, $instance, &$form, &$form_state)
   $instance['required'] = FALSE;
   $instance['description'] = '';
 
+  // Adjust the instance definition to use the default widget of this field type
+  // instead of the hidden widget.
+  if ($instance['widget']['type'] == 'field_hidden') {
+    $field_type = field_info_field_types($field['type']);
+    $default_widget = field_info_widget_types($field_type['default_widget']);
+
+    $instance['widget']['type'] = $default_widget['id'];
+    $instance['widget']['settings'] = $default_widget['settings'];
+  }
+
   // Insert the widget. Since we do not use the "official" instance definition,
   // the whole flow cannot use field_invoke_method().
   $items = (array) $instance['default_value'];
-  $element += $instance->getWidget(FALSE)->form($entity, LANGUAGE_NOT_SPECIFIED, $items, $element, $form_state);
+  $element += $instance->getWidget(TRUE)->form($entity, LANGUAGE_NOT_SPECIFIED, $items, $element, $form_state);
 
   return $element;
 }
@@ -963,7 +973,7 @@ function field_ui_field_edit_form_validate($form, &$form_state) {
 
     // Extract the 'default value'.
     $items = array();
-    $instance->getWidget(FALSE)->extractFormValues($entity, LANGUAGE_NOT_SPECIFIED, $items, $element, $form_state);
+    $instance->getWidget()->extractFormValues($entity, LANGUAGE_NOT_SPECIFIED, $items, $element, $form_state);
 
     // Grab the field definition from $form_state.
     $field_state = field_form_get_state($element['#parents'], $field_name, LANGUAGE_NOT_SPECIFIED, $form_state);
@@ -983,7 +993,7 @@ function field_ui_field_edit_form_validate($form, &$form_state) {
       field_form_set_state($element['#parents'], $field_name, LANGUAGE_NOT_SPECIFIED, $form_state, $field_state);
 
       // Assign reported errors to the correct form element.
-      $instance->getWidget(FALSE)->flagErrors($entity, LANGUAGE_NOT_SPECIFIED, $items, $element, $form_state);
+      $instance->getWidget()->flagErrors($entity, LANGUAGE_NOT_SPECIFIED, $items, $element, $form_state);
     }
   }
 }
@@ -1004,7 +1014,7 @@ function field_ui_field_edit_form_submit($form, &$form_state) {
 
     // Extract field values.
     $items = array();
-    $instance->getWidget(FALSE)->extractFormValues($entity, LANGUAGE_NOT_SPECIFIED, $items, $element, $form_state);
+    $instance->getWidget()->extractFormValues($entity, LANGUAGE_NOT_SPECIFIED, $items, $element, $form_state);
 
     $instance['default_value'] = $items ? $items : NULL;
   }
@@ -1017,7 +1027,7 @@ function field_ui_field_edit_form_submit($form, &$form_state) {
 
   drupal_set_message(t('Saved %label configuration.', array('%label' => $instance['label'])));
 
-  if ($instance['required'] && empty($instance['default_value']) && $instance['widget']['type'] == 'field_hidden') {
+  if ($instance['required'] && empty($instance['default_value']) && empty($instance['default_value_function']) && $instance['widget']['type'] == 'field_hidden') {
     drupal_set_message(t('Field %label is required and uses the "hidden" widget. You might want to configure a default value.', array('%label' => $instance['label'])), 'warning');
   }