diff --git a/core/includes/form.inc b/core/includes/form.inc
index d602d54..b4e51a1 100644
--- a/core/includes/form.inc
+++ b/core/includes/form.inc
@@ -1112,7 +1112,7 @@ function drupal_prepare_form($form_id, &$form, &$form_state) {
     // Ensure that modules can rely on #validate being set.
     $form['#validate'] = array();
     if (isset($form_state['build_info']['callback_object'])) {
-      $form['#validate'][] = array($form_state['build_info']['callback_object'], 'validateForm');
+      $form['#validate'][] = array(clone $form_state['build_info']['callback_object'], 'validateForm');
     }
     // Check for a handler specific to $form_id.
     elseif (function_exists($form_id . '_validate')) {
@@ -1129,7 +1129,7 @@ function drupal_prepare_form($form_id, &$form, &$form_state) {
     // Ensure that modules can rely on #submit being set.
     $form['#submit'] = array();
     if (isset($form_state['build_info']['callback_object'])) {
-      $form['#submit'][] = array($form_state['build_info']['callback_object'], 'submitForm');
+      $form['#submit'][] = array(clone $form_state['build_info']['callback_object'], 'submitForm');
     }
     // Check for a handler specific to $form_id.
     elseif (function_exists($form_id . '_submit')) {
diff --git a/core/modules/entity_reference/entity_reference.module b/core/modules/entity_reference/entity_reference.module
index 54a7bac..07c63ed 100644
--- a/core/modules/entity_reference/entity_reference.module
+++ b/core/modules/entity_reference/entity_reference.module
@@ -193,8 +193,7 @@ function entity_reference_field_entity_update(FieldInterface $field) {
  * Implements hook_field_instance_settings_form().
  */
 function entity_reference_field_instance_settings_form($field, $instance, $form_state) {
-  $field = isset($form_state['entity_reference']['field']) ? $form_state['entity_reference']['field'] : $field;
-  $instance = isset($form_state['entity_reference']['instance']) ? $form_state['entity_reference']['instance'] : $instance;
+  $instance = isset($form_state['instance']) ? $form_state['instance'] : $instance;
 
   $settings = $instance['settings'];
   $settings += array('handler' => 'default');
@@ -222,8 +221,6 @@ function entity_reference_field_instance_settings_form($field, $instance, $form_
       '_entity_reference_field_instance_settings_ajax_process',
     ),
     '#element_validate' => array('_entity_reference_field_instance_settings_validate'),
-    '#field' => $field,
-    '#instance' => $instance,
   );
   $form['handler'] = array(
     '#type' => 'details',
@@ -316,18 +313,15 @@ function _entity_reference_element_validate_filter(&$element, &$form_state) {
 }
 
 /**
- * Form element validation handler; Stores the new values in the form state.
+ * Form element validation handler; Updates the instance settings.
  *
  * @see entity_reference_field_instance_settings_form()
  */
 function _entity_reference_field_instance_settings_validate($form, &$form_state) {
-  $instance = $form['#instance'];
   if (isset($form_state['values']['instance'])) {
-    $instance['settings'] = $form_state['values']['instance']['settings'];
+    unset($form_state['values']['instance']['settings']['handler_submit']);
+    $form_state['instance']['settings'] = $form_state['values']['instance']['settings'];
   }
-  $form_state['entity_reference']['instance'] = $instance;
-
-  unset($form_state['values']['instance']['settings']['handler_submit']);
 }
 
 /**
diff --git a/core/modules/field_ui/lib/Drupal/field_ui/Form/FieldInstanceFormBase.php b/core/modules/field_ui/lib/Drupal/field_ui/Form/FieldInstanceFormBase.php
index 5f7ca61..8b3681c 100644
--- a/core/modules/field_ui/lib/Drupal/field_ui/Form/FieldInstanceFormBase.php
+++ b/core/modules/field_ui/lib/Drupal/field_ui/Form/FieldInstanceFormBase.php
@@ -15,7 +15,7 @@
 use Drupal\field_ui\FieldUI;
 use Symfony\Component\DependencyInjection\ContainerInterface;
 
-abstract class FieldInstanceFormBase implements FormInterface, ControllerInterface {
+abstract class FieldInstanceFormBase implements FormInterface, ControllerInterface, \Serializable {
 
   /**
    * The field instance being edited.
@@ -82,4 +82,22 @@ protected function getNextDestination() {
     return $next_destination;
   }
 
+  /**
+   * {@inheritdoc}
+   */
+  public function serialize() {
+    // We just need the instance id so we can reload it later.
+    return $this->instance->id();
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function unserialize($serialized) {
+    $this->instance = entity_load('field_instance', $serialized);
+
+    $this->entityManager = \Drupal::service('plugin.manager.entity');
+    $this->widgetManager = \Drupal::service('plugin.manager.field.widget');
+  }
+
 }