diff --git a/lib/Drupal/search_api/Entity/Index.php b/lib/Drupal/search_api/Entity/Index.php
index ac9d5b0..9ce7333 100644
--- a/lib/Drupal/search_api/Entity/Index.php
+++ b/lib/Drupal/search_api/Entity/Index.php
@@ -219,11 +219,13 @@ class Index extends ConfigEntityBase implements IndexInterface {
   public function __construct(array $values, $entity_type) {
     // Perform default instance construction.
     parent::__construct($values, $entity_type);
-    // Check if the tracker plugin ID is unconfigured.
+
+    // Check if the tracker plugin ID is not configured.
     if ($this->trackerPluginId === NULL) {
       // Set tracker plugin ID to the default tracker.
       $this->trackerPluginId = \Drupal::config('search_api.settings')->get('default_tracker');
     }
+
     // Merge in default options.
     $this->options += array(
       'cron_limit' => \Drupal::configFactory()->get('search_api.settings')->get('cron_limit'),
@@ -232,7 +234,7 @@ class Index extends ConfigEntityBase implements IndexInterface {
   }
 
   /**
-   * Clones an index object.
+   * {@inheritdoc}
    */
   public function __clone() {
     // Prevent the datasource, tracker and server instance from being cloned.
@@ -302,9 +304,7 @@ class Index extends ConfigEntityBase implements IndexInterface {
    * {@inheritdoc}
    */
   public function hasValidDatasource() {
-    // Get the datasource plugin definition.
     $datasource_plugin_definition = \Drupal::service('search_api.datasource.plugin.manager')->getDefinition($this->datasourcePluginId);
-    // Determine whether the datasource is valid.
     return !empty($datasource_plugin_definition);
   }
 
@@ -334,9 +334,7 @@ class Index extends ConfigEntityBase implements IndexInterface {
    * {@inheritdoc}
    */
   public function hasValidTracker() {
-    // Get the tracker plugin manager.
     $tracker_plugin_definition = \Drupal::service('plugin.manager.search_api.tracker')->getDefinition($this->getTrackerId());
-    // Determine whether the tracker is valid.
     return !empty($tracker_plugin_definition);
   }
 
@@ -840,6 +838,7 @@ class Index extends ConfigEntityBase implements IndexInterface {
    */
   public function resetCaches() {
     $this->datasourcePluginInstance = NULL;
+    $this->trackerPluginInstance = NULL;
     $this->server = NULL;
     $this->fields = NULL;
     $this->fulltextFields = NULL;
@@ -891,7 +890,7 @@ class Index extends ConfigEntityBase implements IndexInterface {
           // $this->queueItems();
         }
       }
-      // Only check if there is a datasource
+      // Only check if there is a datasource.
       if ($this->hasValidDatasource()) {
         // If the index is new (so no update) and the status is enabled, start tracking
         // If the index is not new but the original status is disabled and the new status, start tracking
diff --git a/lib/Drupal/search_api/Plugin/SearchApi/Tracker/DefaultTracker.php b/lib/Drupal/search_api/Plugin/SearchApi/Tracker/DefaultTracker.php
index b85d6d4..629ef38 100644
--- a/lib/Drupal/search_api/Plugin/SearchApi/Tracker/DefaultTracker.php
+++ b/lib/Drupal/search_api/Plugin/SearchApi/Tracker/DefaultTracker.php
@@ -64,7 +64,6 @@ class DefaultTracker extends TrackerPluginBase {
    * {@inheritdoc}
    */
   public static function create(ContainerInterface $container, array $configuration, $plugin_id, $plugin_definition) {
-    /** @var $connection \Drupal\Core\Database\Connection */
     $connection = $container->get('database');
     // Create the plugin instance.
     return new static($connection, $configuration, $plugin_id, $plugin_definition);
@@ -171,7 +170,7 @@ class DefaultTracker extends TrackerPluginBase {
         // Mark operation as successful.
         $success = TRUE;
       }
-      catch (Exception $ex) {
+      catch (\Exception $ex) {
         // Log exception to watchdog.
         watchdog_exception('Search API', $ex);
         // Rollback any changes made to the database.
@@ -215,7 +214,7 @@ class DefaultTracker extends TrackerPluginBase {
         // Mark operation as successful.
         $success = TRUE;
       }
-      catch (Exception $ex) {
+      catch (\Exception $ex) {
         // Log exception to watchdog.
         watchdog_exception('Search API', $ex);
         // Rollback any changes made to the database.
@@ -257,7 +256,7 @@ class DefaultTracker extends TrackerPluginBase {
         // Mark operation as successful.
         $success = TRUE;
       }
-      catch (Exception $ex) {
+      catch (\Exception $ex) {
         // Log exception to watchdog.
         watchdog_exception('Search API', $ex);
         // Rollback any changes made to the database.
@@ -303,7 +302,7 @@ class DefaultTracker extends TrackerPluginBase {
         // Mark operation as successful.
         $success = TRUE;
       }
-      catch (Exception $ex) {
+      catch (\Exception $ex) {
         // Log exception to watchdog.
         watchdog_exception('Search API', $ex);
         // Rollback any changes made to the database.
@@ -413,7 +412,7 @@ class DefaultTracker extends TrackerPluginBase {
         // Mark operation as successful.
         $success = TRUE;
       }
-      catch (Exception $ex) {
+      catch (\Exception $ex) {
         // Log exception to watchdog.
         watchdog_exception('Search API', $ex);
         // Rollback any changes made to the database.