diff --git a/core/modules/filter/filter.module b/core/modules/filter/filter.module
index 873e7d27..245087e 100644
--- a/core/modules/filter/filter.module
+++ b/core/modules/filter/filter.module
@@ -135,9 +135,11 @@ function filter_menu() {
     'type' => MENU_LOCAL_ACTION,
   );
   $items['admin/config/content/formats/manage/%'] = array(
+    'title callback' => 'filter_admin_format_title',
+    'title arguments' => array(5),
     'route_name' => 'filter_format_edit',
   );
-  $items['admin/config/content/formats/manage/%filter_format/disable'] = array(
+  $items['admin/config/content/formats/manage/%/disable'] = array(
     'title' => 'Disable text format',
     'route_name' => 'filter_admin_disable',
   );
@@ -184,16 +186,15 @@ function filter_format_exists($format_id) {
 /**
  * Displays a text format form title.
  *
- * @param object $format_id
- *   A format object.
+ * @param string $format_id
+ *   A format ID.
  *
  * @return string
  *   The name of the format.
- *
- * @see filter_menu()
  */
-function filter_admin_format_title($format) {
-  return $format->name;
+function filter_admin_format_title($format_id) {
+  $format = filter_format_load($format_id);
+  return $format->label();
 }
 
 /**
diff --git a/core/modules/filter/lib/Drupal/filter/FilterFormatEditFormController.php b/core/modules/filter/lib/Drupal/filter/FilterFormatEditFormController.php
index 695239d..09a62dd 100644
--- a/core/modules/filter/lib/Drupal/filter/FilterFormatEditFormController.php
+++ b/core/modules/filter/lib/Drupal/filter/FilterFormatEditFormController.php
@@ -7,6 +7,8 @@
 
 namespace Drupal\filter;
 
+use Symfony\Component\HttpKernel\Exception\NotFoundHttpException;
+
 /**
  * Provides a form controller for adding a filter format.
  */
@@ -16,6 +18,10 @@ class FilterFormatEditFormController extends FilterFormatFormControllerBase {
    * {@inheritdoc}
    */
   public function form(array $form, array &$form_state) {
+    if (!$this->entity->status()) {
+      throw new NotFoundHttpException();
+    }
+
     drupal_set_title($this->entity->label());
     $form = parent::form($form, $form_state);
     $form['roles']['#default_value'] = array_keys(filter_get_roles_by_format($this->entity));
diff --git a/core/modules/filter/lib/Drupal/filter/FilterFormatFormControllerBase.php b/core/modules/filter/lib/Drupal/filter/FilterFormatFormControllerBase.php
index 0602ad8..d9fc159 100644
--- a/core/modules/filter/lib/Drupal/filter/FilterFormatFormControllerBase.php
+++ b/core/modules/filter/lib/Drupal/filter/FilterFormatFormControllerBase.php
@@ -10,6 +10,7 @@
 use Drupal\Core\Config\ConfigFactory;
 use Drupal\Core\Entity\EntityControllerInterface;
 use Drupal\Core\Entity\EntityFormController;
+use Drupal\Core\Entity\Query\QueryFactory;
 use Symfony\Component\DependencyInjection\ContainerInterface;
 
 /**
@@ -25,10 +26,18 @@
   protected $configFactory;
 
   /**
+   * The entity query factory.
+   *
+   * @var \Drupal\Core\Entity\Query\QueryFactory
+   */
+  protected $queryFactory;
+
+  /**
    * Constructs a new FilterFormatFormControllerBase.
    */
-  public function __construct(ConfigFactory $config_factory) {
+  public function __construct(ConfigFactory $config_factory, QueryFactory $query_factory) {
     $this->configFactory = $config_factory;
+    $this->queryFactory = $query_factory;
   }
 
   /**
@@ -36,7 +45,8 @@ public function __construct(ConfigFactory $config_factory) {
    */
   public static function createInstance(ContainerInterface $container, $entity_type, array $entity_info) {
     return new static(
-      $container->get('config.factory')
+      $container->get('config.factory'),
+      $container->get('entity.query')
     );
   }
 
@@ -186,6 +196,14 @@ public function validate(array $form, array &$form_state) {
     // Ensure that the values to be saved later are exactly the ones validated.
     form_set_value($form['format'], $format_format, $form_state);
     form_set_value($form['name'], $format_name, $form_state);
+
+    $format_exists = $this->queryFactory
+      ->get('filter_format')
+      ->condition('name', $format_name)
+      ->execute();
+    if ($format_exists) {
+      form_set_error('name', t('Text format names must be unique. A format named %name already exists.', array('%name' => $format_name)));
+    }
   }
 
   /**