diff --git a/src/Form/FacetDisplayForm.php b/src/Form/FacetDisplayForm.php
index 0b42098..3cd08e5 100644
--- a/src/Form/FacetDisplayForm.php
+++ b/src/Form/FacetDisplayForm.php
@@ -51,7 +51,7 @@ class FacetDisplayForm extends EntityForm {
   /**
    * The plugin manager for sort processors.
    *
-   * @var \Drupal\facets\Widget\WidgetPluginManager
+   * @var \Drupal\facets\SortProcessor\SortProcessorPluginManager
    */
   protected $sortProcessorPluginManager;
 
@@ -543,7 +543,7 @@ class FacetDisplayForm extends EntityForm {
       // The sort processor handler should have the settings for all sorting
       // facets.
       if ($processor_id === 'sort_processor_handler') {
-        $new_settings['settings'] = $values['facet_sorting'];
+        $new_settings['settings'] = isset($values['facet_sorting']) ? $values['facet_sorting'] : [];
       }
       $facet->addProcessor($new_settings);
     }
diff --git a/src/Plugin/facets/sort_processor/ActiveWidgetOrderProcessor.php b/src/Plugin/facets/sort_processor/ActiveWidgetOrderProcessor.php
index e81ab36..f18cc84 100644
--- a/src/Plugin/facets/sort_processor/ActiveWidgetOrderProcessor.php
+++ b/src/Plugin/facets/sort_processor/ActiveWidgetOrderProcessor.php
@@ -11,10 +11,7 @@ use Drupal\facets\SortProcessor\SortProcessorPluginBase;
  * @FacetsSortProcessor(
  *   id = "active_widget_order",
  *   label = @Translation("Sort by active state"),
- *   description = @Translation("Sorts the widget results by active state."),
- *   stages = {
- *     "build" = 50
- *   }
+ *   description = @Translation("Sorts the widget results by active state.")
  * )
  */
 class ActiveWidgetOrderProcessor extends SortProcessorPluginBase {
diff --git a/src/Plugin/facets/sort_processor/CountWidgetOrderProcessor.php b/src/Plugin/facets/sort_processor/CountWidgetOrderProcessor.php
index 7484f94..87d95a2 100644
--- a/src/Plugin/facets/sort_processor/CountWidgetOrderProcessor.php
+++ b/src/Plugin/facets/sort_processor/CountWidgetOrderProcessor.php
@@ -11,10 +11,7 @@ use Drupal\facets\SortProcessor\SortProcessorPluginBase;
  * @FacetsSortProcessor(
  *   id = "count_widget_order",
  *   label = @Translation("Sort by count"),
- *   description = @Translation("Sorts the widget results by count."),
- *   stages = {
- *     "build" = 50
- *   }
+ *   description = @Translation("Sorts the widget results by count.")
  * )
  */
 class CountWidgetOrderProcessor extends SortProcessorPluginBase {
diff --git a/src/Plugin/facets/sort_processor/DisplayValueWidgetOrderProcessor.php b/src/Plugin/facets/sort_processor/DisplayValueWidgetOrderProcessor.php
index 3e1d090..9e1c1d3 100644
--- a/src/Plugin/facets/sort_processor/DisplayValueWidgetOrderProcessor.php
+++ b/src/Plugin/facets/sort_processor/DisplayValueWidgetOrderProcessor.php
@@ -3,6 +3,7 @@
 namespace Drupal\facets\Plugin\facets\sort_processor;
 
 use Drupal\Component\Transliteration\TransliterationInterface;
+use Drupal\Core\Plugin\ContainerFactoryPluginInterface;
 use Drupal\facets\Result\Result;
 use Drupal\facets\SortProcessor\SortProcessorPluginBase;
 use Symfony\Component\DependencyInjection\ContainerInterface;
@@ -13,13 +14,10 @@ use Symfony\Component\DependencyInjection\ContainerInterface;
  * @FacetsSortProcessor(
  *   id = "display_value_widget_order",
  *   label = @Translation("Sort by display value"),
- *   description = @Translation("Sorts the widget results by display value."),
- *   stages = {
- *     "build" = 50
- *   }
+ *   description = @Translation("Sorts the widget results by display value.")
  * )
  */
-class DisplayValueWidgetOrderProcessor extends SortProcessorPluginBase {
+class DisplayValueWidgetOrderProcessor extends SortProcessorPluginBase implements ContainerFactoryPluginInterface  {
 
   /**
    * The transliteration service.
diff --git a/src/Plugin/facets/sort_processor/RawValueWidgetOrderProcessor.php b/src/Plugin/facets/sort_processor/RawValueWidgetOrderProcessor.php
index 11fb0cb..d627300 100644
--- a/src/Plugin/facets/sort_processor/RawValueWidgetOrderProcessor.php
+++ b/src/Plugin/facets/sort_processor/RawValueWidgetOrderProcessor.php
@@ -11,10 +11,7 @@ use Drupal\facets\SortProcessor\SortProcessorPluginBase;
  * @FacetsSortProcessor(
  *   id = "raw_value_widget_order",
  *   label = @Translation("Sort by raw value"),
- *   description = @Translation("Sorts the widget results by raw value."),
- *   stages = {
- *     "build" = 50
- *   }
+ *   description = @Translation("Sorts the widget results by raw value.")
  * )
  */
 class RawValueWidgetOrderProcessor extends SortProcessorPluginBase {
diff --git a/src/SortProcessor/SortProcessorPluginManager.php b/src/SortProcessor/SortProcessorPluginManager.php
index 5ac0efd..e910389 100644
--- a/src/SortProcessor/SortProcessorPluginManager.php
+++ b/src/SortProcessor/SortProcessorPluginManager.php
@@ -7,7 +7,7 @@ use Drupal\Core\Extension\ModuleHandlerInterface;
 use Drupal\Core\Plugin\DefaultPluginManager;
 
 /**
- * Manages URL processor plugins.
+ * Manages sort processor plugins.
  *
  * @see \Drupal\facets\Annotation\FacetsProcessor
  * @see \Drupal\facets\Processor\ProcessorInterface