diff --git a/core/modules/language/src/Plugin/Block/LanguageBlock.php b/core/modules/language/src/Plugin/Block/LanguageBlock.php
index 7aa9bb8..9e12afb 100644
--- a/core/modules/language/src/Plugin/Block/LanguageBlock.php
+++ b/core/modules/language/src/Plugin/Block/LanguageBlock.php
@@ -9,6 +9,8 @@
 
 use Drupal\Core\Block\BlockBase;
 use Drupal\Core\Path\PathMatcherInterface;
+use Drupal\Core\Form\FormStateInterface;
+use Drupal\Core\Language\LanguageManager;
 use Drupal\Core\Session\AccountInterface;
 use Drupal\Core\Language\LanguageManagerInterface;
 use Drupal\Core\Plugin\ContainerFactoryPluginInterface;
@@ -116,4 +118,20 @@ public function getCacheMaxAge() {
     return 0;
   }
 
+  /**
+   * {@inheritdoc}
+   */
+  public function blockForm($form, FormStateInterface $form_state) {
+    $form = parent::blockForm($form, $form_state);
+    $path = drupal_is_front_page() ? '<front>' : Url::fromRoute('<current>');
+    list(, $type) = explode(':', $this->getPluginId());
+    $links = $this->languageManager->getLanguageSwitchLinks($type, $path);
+    // Warn the user that if there are no links to show, the block won't appear.
+    if (empty($links)) {
+      drupal_set_message($this->t('You do not have any language detection method enabled that provides URL based detection. The language switcher module will not be shown.'), 'warning');
+    }
+
+    return $form;
+  }
+
 }