reverted:
--- b/core/modules/field/lib/Drupal/field/Entity/Field.php
+++ a/core/modules/field/lib/Drupal/field/Entity/Field.php
@@ -710,16 +710,19 @@
     }
   }
 
+  /**
+   * {@inheritdoc}
+   */
+  public function serialize() {
+    // Only store the definition, not external objects or derived data.
+    return serialize($this->getExportProperties());
-  public function __sleep() {
-    return array_intersect(array_keys($this->getExportProperties()), array_keys(get_object_vars($this)));
   }
 
+  /**
+   * {@inheritdoc}
+   */
+  public function unserialize($serialized) {
+    $this->__construct(unserialize($serialized));
-  public function __wakeup() {
-    // @todo array_filter() not great...
-    $new_obj = new static(array_filter(get_object_vars($this)));
-    foreach (get_object_vars($new_obj) as $key => $value) {
-      $this->{$key} = $value;
-    }
   }
 
   /**
reverted:
--- b/core/modules/field/lib/Drupal/field/Entity/FieldInstance.php
+++ a/core/modules/field/lib/Drupal/field/Entity/FieldInstance.php
@@ -643,16 +643,19 @@
     unset($this->{$offset});
   }
 
+  /**
+   * {@inheritdoc}
+   */
+  public function serialize() {
+    // Only store the definition, not external objects or derived data.
+    return serialize($this->getExportProperties());
-  public function __sleep() {
-    return array_intersect(array_keys($this->getExportProperties()), array_keys(get_object_vars($this)));
   }
 
+  /**
+   * {@inheritdoc}
+   */
+  public function unserialize($serialized) {
+    $this->__construct(unserialize($serialized));
-  public function __wakeup() {
-    // @todo array_filter() not great...
-    $new_obj = new static(array_filter(get_object_vars($this)));
-    foreach (get_object_vars($new_obj) as $key => $value) {
-      $this->{$key} = $value;
-    }
   }
 
 }
reverted:
--- b/core/modules/field/lib/Drupal/field/FieldInstanceInterface.php
+++ a/core/modules/field/lib/Drupal/field/FieldInstanceInterface.php
@@ -13,7 +13,7 @@
 /**
  * Provides an interface defining a field instance entity.
  */
+interface FieldInstanceInterface extends ConfigEntityInterface, FieldDefinitionInterface, \ArrayAccess, \Serializable {
-interface FieldInstanceInterface extends ConfigEntityInterface, FieldDefinitionInterface, \ArrayAccess {
 
   /**
    * Returns the field entity for this instance.
reverted:
--- b/core/modules/field/lib/Drupal/field/FieldInterface.php
+++ a/core/modules/field/lib/Drupal/field/FieldInterface.php
@@ -13,7 +13,7 @@
 /**
  * Provides an interface defining a field entity.
  */
+interface FieldInterface extends ConfigEntityInterface, FieldDefinitionInterface, \ArrayAccess, \Serializable {
-interface FieldInterface extends ConfigEntityInterface, FieldDefinitionInterface, \ArrayAccess {
 
   /**
    * Returns the field schema.