diff --git a/core/lib/Drupal/Component/Plugin/Discovery/DiscoveryInterface.php b/core/lib/Drupal/Component/Plugin/Discovery/DiscoveryInterface.php
index 66e6a2ec03..9ae3b695f7 100644
--- a/core/lib/Drupal/Component/Plugin/Discovery/DiscoveryInterface.php
+++ b/core/lib/Drupal/Component/Plugin/Discovery/DiscoveryInterface.php
@@ -22,7 +22,7 @@
    *   A plugin definition, or NULL if the plugin ID is invalid and
    *   $exception_on_invalid is FALSE.
    *
-   * @throws \Drupal\Component\Plugin\Exception\PluginNotFoundException
+   * @throws \Drupal\Component\Plugin\Exception\PluginNotFoundExceptuion
    *   Thrown if $plugin_id is invalid and $exception_on_invalid is TRUE.
    */
   public function getDefinition($plugin_id, $exception_on_invalid = TRUE);
diff --git a/core/modules/language/src/Plugin/LanguageNegotiation/LanguageNegotiationSession.php b/core/modules/language/src/Plugin/LanguageNegotiation/LanguageNegotiationSession.php
index 971e907aae..b14f509e5f 100644
--- a/core/modules/language/src/Plugin/LanguageNegotiation/LanguageNegotiationSession.php
+++ b/core/modules/language/src/Plugin/LanguageNegotiation/LanguageNegotiationSession.php
@@ -117,6 +117,13 @@ public function processOutbound($path, &$options = [], Request $request = NULL,
         }
       }
     }
+
+    // To avoid page cache duplicates, remove the language query if the default
+    // language is set.
+    if ($this->currentUser->isAnonymous() && $cache && isset($options['query'][$this->queryParam]) && $options['query'][$this->queryParam] == $default) {
+      unset($options['query'][$this->queryParam]);
+    }
+
     return $path;
   }
 
@@ -142,12 +149,12 @@ public function getLanguageSwitchLinks(Request $request, $type, Url $url) {
         'attributes' => ['class' => ['language-link']],
         'query' => $query,
       ];
-      if ($language_query != $langcode) {
-        $links[$langcode]['query'][$param] = $langcode;
-      }
-      else {
+      if ($langcode == $language_query) {
         $links[$langcode]['attributes']['class'][] = 'session-active';
       }
+      // Always set the language query parameter. It may be removed in
+      // LanguageNegotiationSession::processOutbound().
+      $links[$langcode]['query'][$param] = $langcode;
     }
 
     return $links;