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 3d258b2..8073b18 100644
--- a/core/lib/Drupal/Core/Field/Plugin/Field/FieldType/EntityReferenceItem.php
+++ b/core/lib/Drupal/Core/Field/Plugin/Field/FieldType/EntityReferenceItem.php
@@ -16,6 +16,7 @@
 use Drupal\Core\Field\FieldItemBase;
 use Drupal\Core\TypedData\DataDefinition;
 use Drupal\Core\TypedData\DataReferenceDefinition;
+use Drupal\entity_reference\Exception\MissingDefaultValueException;
 
 /**
  * Defines the 'entity_reference' entity field type.
@@ -255,7 +256,12 @@ public static function calculateDependencies(FieldDefinitionInterface $field_def
       foreach ($field_definition->default_value as $default_value) {
         if (is_array($default_value) && isset($default_value['target_uuid'])) {
           $entity = \Drupal::entityManager()->loadEntityByUuid($target_entity_type->id(), $default_value['target_uuid']);
-          $dependencies[$key][] = $entity->getConfigDependencyName();
+          if ($entity) {
+            $dependencies[$key][] = $entity->getConfigDependencyName();
+          }
+          else {
+            throw new MissingDefaultValueException($target_entity_type->id(), $default_value['target_uuid'], $field_definition->getName());
+          }
         }
       }
     }
diff --git a/core/modules/config/src/Tests/AssertConfigEntityImportTrait.php b/core/modules/config/src/Tests/AssertConfigEntityImportTrait.php
new file mode 100644
index 0000000..0f8ad2b
--- /dev/null
+++ b/core/modules/config/src/Tests/AssertConfigEntityImportTrait.php
@@ -0,0 +1,42 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\config\Tests\AssertConfigEntityImportTrait.
+ */
+
+namespace Drupal\config\Tests;
+
+use Drupal\Core\Config\Entity\ConfigEntityInterface;
+
+/**
+ * Provides test assertions for testing config entity synchronisation.
+ *
+ * Can be used by test classes that extend \Drupal\simpletest\WebTestBase or
+ * \Drupal\simpletest\KernelTestBase.
+ */
+trait AssertConfigEntityImportTrait {
+
+  /**
+   * Asserts that a config entity can be imported without changing it.
+   *
+   * @param \Drupal\Core\Config\Entity\ConfigEntityInterface $entity
+   *   The config entity to test importing.
+   */
+  public function assertConfigEntityImport(ConfigEntityInterface $entity) {
+    // Save original config information.
+    $entity_uuid = $entity->uuid();
+    $entity_type_id = $entity->getEntityTypeId();
+    $original_data = $entity->toArray();
+    // Copy everything to staging.
+    $this->copyConfig(\Drupal::service('config.storage'), \Drupal::service('config.storage.staging'));
+    // Delete the configuration from active. Don't worry about side effects of
+    // deleting config like fields cleaning up field storages. The coming import
+    // should recreate everything as necessary.
+    $entity->delete();
+    $this->configImporter()->reset()->import();
+    $imported_entity = \Drupal::entityManager()->loadEntityByUuid($entity_type_id, $entity_uuid);
+    $this->assertIdentical($original_data, $imported_entity->toArray());
+  }
+
+}
diff --git a/core/modules/entity_reference/src/Exception/MissingDefaultValueException.php b/core/modules/entity_reference/src/Exception/MissingDefaultValueException.php
new file mode 100644
index 0000000..2070e27
--- /dev/null
+++ b/core/modules/entity_reference/src/Exception/MissingDefaultValueException.php
@@ -0,0 +1,33 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\entity_reference\RecursiveRenderingException.
+ */
+
+namespace Drupal\entity_reference\Exception;
+
+/**
+ * Exception thrown when an entity reference has a nonexistent default value.
+ */
+class MissingDefaultValueException extends \Exception {
+  /**
+   * Construct an MissingDefaultValueException exception.
+   *
+   * @param string $entity_type_id
+   *   The entity type ID of the missing entity.
+   * @param string $uuid
+   *   The UUID of the missing entity.
+   * @param string $field_name
+   *   The entity reference field name.
+   *
+   * @see \Exception for remaining parameters.
+   */
+  public function __construct($entity_type_id, $uuid, $field_name, $message = '', $code = 0, \Exception $previous = NULL) {
+    if (empty($message)) {
+      $message = sprintf("Default value '%s' of entity type '%s' for '%s' field was not found.", $uuid, $entity_type_id, $field_name);
+    }
+    parent::__construct($message, $code, $previous);
+  }
+
+}
diff --git a/core/modules/entity_reference/src/Tests/EntityReferenceIntegrationTest.php b/core/modules/entity_reference/src/Tests/EntityReferenceIntegrationTest.php
index bc28654..01994bf 100644
--- a/core/modules/entity_reference/src/Tests/EntityReferenceIntegrationTest.php
+++ b/core/modules/entity_reference/src/Tests/EntityReferenceIntegrationTest.php
@@ -8,6 +8,9 @@
 namespace Drupal\entity_reference\Tests;
 
 use Drupal\Component\Utility\String;
+use Drupal\config\Tests\AssertConfigEntityImportTrait;
+use Drupal\entity_reference\Exception\MissingDefaultValueException;
+use Drupal\field\Entity\FieldConfig;
 use Drupal\simpletest\WebTestBase;
 
 /**
@@ -16,6 +19,7 @@
  * @group entity_reference
  */
 class EntityReferenceIntegrationTest extends WebTestBase {
+  use AssertConfigEntityImportTrait;
 
   /**
    * The entity type used in this test.
@@ -139,6 +143,21 @@ public function testSupportedEntityTypesAndWidgets() {
       // Ensure the configuration has the expected dependency on the entity that
       // is being used a default value.
       $this->assertTrue(in_array($referenced_entities[0]->getConfigDependencyName(), $config_entity['dependencies'][$key]), String::format('Expected @type dependency @name found', ['@type' => $key, '@name' => $referenced_entities[0]->getConfigDependencyName()]));
+      // Ensure that the field can be imported without change even after the
+      // default value deleted.
+      $referenced_entities[0]->delete();
+      $this->assertConfigEntityImport(FieldConfig::loadByName($this->entityType, $this->bundle, $this->fieldName));
+
+      // Test re-saving the field now that the default value does not exist.
+      $msg = 'Expected MissingDefaultValueException exception thrown.';
+      try {
+        FieldConfig::loadByName($this->entityType, $this->bundle, $this->fieldName)->save();
+        $this->fail($msg);
+      }
+      catch (MissingDefaultValueException $e) {
+        $this->pass($msg);
+        $this->assertEqual($e->getMessage(), sprintf("Default value '%s' of entity type '%s' for '%s' field was not found.", $referenced_entities[0]->uuid(), $referenced_entities[0]->getEntityTypeId(), $this->fieldName));
+      }
     }
   }