Update to drupal 8.0.0-rc1. For more information, see https://www.drupal.org/node/2582663

core/modules/field/field.install

@@ -0,0 +1,70 @@
+<?php
+
+/**
+ * @file
+ * Install, update and uninstall functions for the field module.
+ */
+
+use Drupal\Core\Field\Plugin\Field\FieldType\EntityReferenceItem;
+
+/**
+ * Removes the stale 'target_bundle' storage setting on entity_reference fields.
+ */
+function field_update_8001() {
+  $config = \Drupal::configFactory();
+  /** @var \Drupal\Core\Field\FieldTypePluginManager $field_type_manager */
+  $field_type_manager = \Drupal::service('plugin.manager.field.field_type');
+
+  // Iterate on all fields storage.
+  foreach ($config->listAll('field.storage.') as $field_id) {
+    $field_storage = $config->getEditable($field_id);
+    $class = $field_type_manager->getPluginClass($field_storage->get('type'));
+
+    // Deal only with entity reference fields and descendants.
+    if ($class == EntityReferenceItem::class || is_subclass_of($class, EntityReferenceItem::class)) {
+      // Remove 'target_bundle' from settings.
+      $field_storage->clear('settings.target_bundle')->save(TRUE);
+    }
+  }
+}
+
+/**
+ * The 'entity_reference' field type is now provided by core.
+ */
+function field_update_8002() {
+  $config_factory = \Drupal::configFactory();
+
+  // Iterate on all configuration entities.
+  foreach ($config_factory->listAll() as $id) {
+    $changed = FALSE;
+    $config = $config_factory->getEditable($id);
+
+    // Update field storage configurations.
+    if (strpos($id, 'field.storage.') === 0) {
+      // Deal only with entity reference fields.
+      if ($config->get('type') == 'entity_reference') {
+        // Fix the type provider.
+        $config->set('module', 'core');
+        $changed = TRUE;
+      }
+    }
+
+    // Remove entity_reference module dependency from any configuration entity.
+    if ($dependencies = $config->get('dependencies.module')) {
+      if (($delta = array_search('entity_reference', $dependencies)) !== FALSE) {
+        unset($dependencies[$delta]);
+        if ($dependencies) {
+          $config->set('dependencies.module', array_values($dependencies));
+        }
+        else {
+          $config->clear('dependencies.module');
+        }
+        $changed = TRUE;
+      }
+    }
+
+    if ($changed) {
+      $config->save(TRUE);
+    }
+  }
+}