diff --git a/src/Form/IndexForm.php b/src/Form/IndexForm.php
index 5f3f933..447f0df 100644
--- a/src/Form/IndexForm.php
+++ b/src/Form/IndexForm.php
@@ -8,7 +8,6 @@
 namespace Drupal\search_api\Form;
 
 use Drupal\Component\Utility\Html;
-use Drupal\Component\Utility\SafeMarkup;
 use Drupal\Core\Cache\Cache;
 use Drupal\Core\Entity\EntityForm;
 use Drupal\Core\Entity\EntityManagerInterface;
diff --git a/src/Form/IndexStatusForm.php b/src/Form/IndexStatusForm.php
index a39717a..1d5e6f6 100644
--- a/src/Form/IndexStatusForm.php
+++ b/src/Form/IndexStatusForm.php
@@ -44,7 +44,7 @@ class IndexStatusForm extends FormBase {
         $form['tracking'] = array(
           '#type' => 'details',
           '#title' => $this->t('Track items for index'),
-          '#description' => $this->t('Not all items have been tracked for this index. This means, the displayed index status is incomplete and not all items will currently be indexed.'),
+          '#description' => $this->t('Not all items have been tracked for this index. This means the displayed index status is incomplete and not all items will currently be indexed.'),
           '#open' => TRUE,
           '#attributes' => array(
             'class' => array('container-inline'),
diff --git a/src/Task/IndexTaskManager.php b/src/Task/IndexTaskManager.php
index 89f5b8a..864262d 100644
--- a/src/Task/IndexTaskManager.php
+++ b/src/Task/IndexTaskManager.php
@@ -121,7 +121,7 @@ class IndexTaskManager implements IndexTaskManagerInterface {
     if (!empty($index_state['status'])) {
       $batch_definition = array(
         'operations' => array(
-          array(array($this, 'processBatch'), array($index)),
+          array(array($this, 'processBatch'), array($index->id())),
         ),
         'finished' => array($this, 'finishBatch'),
       );
@@ -133,13 +133,15 @@ class IndexTaskManager implements IndexTaskManagerInterface {
   /**
    * Adds one page of items to the tracker as part of a batch operation.
    *
-   * @param \Drupal\search_api\IndexInterface $index
-   *   The index on which items should be indexed.
+   * @param string $index_id
+   *   The ID of the index on which items should be indexed.
    * @param array $context
    *   The current batch context, as defined in the @link batch Batch operations
    *   @endlink documentation.
    */
-  public function processBatch(IndexInterface $index, array &$context) {
+  public function processBatch($index_id, array &$context) {
+    /** @var \Drupal\search_api\IndexInterface $index */
+    $index = $this->entityManager->getStorage('search_api_index')->load($index_id);
     $added = $this->addItemsOnce($index);
     if ($added === NULL) {
       $context['finished'] = 1;
@@ -268,4 +270,23 @@ class IndexTaskManager implements IndexTaskManagerInterface {
     return 'search_api.index.' . $index->id() . '.tasks';
   }
 
+  /**
+   * Implements the magic __sleep() method.
+   *
+   * Prevents the any properties from being serialized.
+   */
+  public function __sleep() {
+    return array();
+  }
+
+  /**
+   * Implements the magic __wakeup() method.
+   *
+   * Reloads the services into this object's properties.
+   */
+  public function __wakeup() {
+    $this->state = \Drupal::state();
+    $this->entityManager = \Drupal::entityManager();
+  }
+
 }