diff --git a/core/lib/Drupal/Core/Entity/ContentEntityBase.php b/core/lib/Drupal/Core/Entity/ContentEntityBase.php
index 1d69be2..d77d52c 100644
--- a/core/lib/Drupal/Core/Entity/ContentEntityBase.php
+++ b/core/lib/Drupal/Core/Entity/ContentEntityBase.php
@@ -413,7 +413,7 @@ public function __sleep() {
     // Get the values of instantiated field objects, only serialize the values.
     foreach ($this->fields as $name => $fields) {
       foreach ($fields as $langcode => $field) {
-        $this->values[$name][$langcode] = $field->getValue();
+        $this->values[$name][$langcode] = $field->getValue(TRUE);
       }
     }
     $this->fields = array();
diff --git a/core/lib/Drupal/Core/Field/Plugin/Field/FieldType/EntityReferenceItem.php b/core/lib/Drupal/Core/Field/Plugin/Field/FieldType/EntityReferenceItem.php
index 63bd90d..a6b7afe 100644
--- a/core/lib/Drupal/Core/Field/Plugin/Field/FieldType/EntityReferenceItem.php
+++ b/core/lib/Drupal/Core/Field/Plugin/Field/FieldType/EntityReferenceItem.php
@@ -189,7 +189,7 @@ public function setValue($values, $notify = TRUE) {
         // If the entity has been saved and we're trying to set both the
         // target_id and the entity values with a non-null target ID, then the
         // value for target_id should match the ID of the entity value.
-        if (!$this->entity->isNew() && $values['target_id'] !== NULL && ($entity_id !== $values['target_id'])) {
+        if (!$this->entity->isNew() && $values['target_id'] !== NULL && ($entity_id != $values['target_id'])) {
           throw new \InvalidArgumentException('The target id and entity passed to the entity reference item do not match.');
         }
       }
@@ -204,12 +204,12 @@ public function setValue($values, $notify = TRUE) {
   /**
    * {@inheritdoc}
    */
-  public function getValue() {
+  public function getValue($include_computed = FALSE) {
     $values = parent::getValue();
 
     // If there is an unsaved entity, return it as part of the field item values
     // to ensure idempotency of getValue() / setValue().
-    if ($this->hasNewEntity()) {
+    if ($include_computed || $this->hasNewEntity()) {
       $values['entity'] = $this->entity;
     }
     return $values;
diff --git a/core/modules/node/src/Entity/NodeType.php b/core/modules/node/src/Entity/NodeType.php
index 91d8a90..923f9e5 100644
--- a/core/modules/node/src/Entity/NodeType.php
+++ b/core/modules/node/src/Entity/NodeType.php
@@ -90,7 +90,7 @@ class NodeType extends ConfigEntityBundleBase implements NodeTypeInterface {
    *
    * @var int
    */
-  protected $preview_mode = DRUPAL_OPTIONAL;
+  protected $preview_mode = 1;
 
   /**
    * Display setting for author and date Submitted by post information.