diff --git a/core/lib/Drupal/Core/Config/ConfigInstaller.php b/core/lib/Drupal/Core/Config/ConfigInstaller.php
index 14f44e9..aa7823f 100644
--- a/core/lib/Drupal/Core/Config/ConfigInstaller.php
+++ b/core/lib/Drupal/Core/Config/ConfigInstaller.php
@@ -455,8 +455,7 @@ public function checkConfigurationToInstall($type, $name) {
     $profile_storages = $this->getProfileStorages($name);
 
     // Check the dependencies of configuration provided by the module.
-    $missing_dependencies = [];
-    $invalid_default_config = $this->findDefaultConfigWithUnmetDependencies($storage, $enabled_extensions, $profile_storages, $missing_dependencies);
+    list($invalid_default_config, $missing_dependencies) = $this->findDefaultConfigWithUnmetDependencies($storage, $enabled_extensions, $profile_storages);
     if (!empty($invalid_default_config)) {
       throw UnmetDependenciesException::create($name, array_unique($missing_dependencies));
     }
@@ -484,14 +483,15 @@ public function checkConfigurationToInstall($type, $name) {
    * @param \Drupal\Core\Config\StorageInterface[] $profile_storages
    *   An array of storage interfaces containing profile configuration to check
    *   for overrides.
-   * @param array $missing_dependencies
-   *   (optional) An array that will be filled with the list of missing
-   *   dependencies, keyed by by the dependents' names.
    *
    * @return array
-   *   List of configuration that has unmet dependencies.
+   *   An array containing:
+   *     - A list of configuration that has unmet dependencies.
+   *     - An array that will be filled with the list of missing
+   *       dependencies, keyed by by the dependents' names.
    */
   protected function findDefaultConfigWithUnmetDependencies(StorageInterface $storage, array $enabled_extensions, array $profile_storages = [], array &$missing_dependencies = []) {
+    $missing_dependencies = [];
     $config_to_create = $this->getConfigToCreate($storage, StorageInterface::DEFAULT_COLLECTION, '', $profile_storages);
     $all_config = array_merge($this->configFactory->listAll(), array_keys($config_to_create));
     foreach ($config_to_create as $config_name => $config) {
@@ -499,7 +499,10 @@ protected function findDefaultConfigWithUnmetDependencies(StorageInterface $stor
         $missing_dependencies[$config_name] = $missing;
       }
     }
-    return array_intersect_key($config_to_create, $missing_dependencies);
+    return [
+      array_intersect_key($config_to_create, $missing_dependencies),
+      $missing_dependencies,
+    ];
   }
 
   /**
diff --git a/core/lib/Drupal/Core/Config/UnmetDependenciesException.php b/core/lib/Drupal/Core/Config/UnmetDependenciesException.php
index e49afc9..30641ec 100644
--- a/core/lib/Drupal/Core/Config/UnmetDependenciesException.php
+++ b/core/lib/Drupal/Core/Config/UnmetDependenciesException.php
@@ -69,10 +69,10 @@ public function getExtension() {
    */
   public function getTranslatedMessage(TranslationInterface $string_translation, $extension) {
     return $string_translation->translate(
-      'Unable to install @extension due to unmet dependencies: @config_names',
+      'Unable to install %extension due to unmet dependencies: %config_names',
       [
-        '@config_names' => self::formatConfigObjectList($this->configObjects),
-        '@extension' => $extension,
+        '%config_names' => static::formatConfigObjectList($this->configObjects),
+        '%extension' => $extension,
       ]
     );
   }
@@ -89,10 +89,10 @@ public function getTranslatedMessage(TranslationInterface $string_translation, $
    * @return \Drupal\Core\Config\PreExistingConfigException
    */
   public static function create($extension, array $config_objects) {
-    $message = SafeMarkup::format('Configuration objects provided by @extension have unmet dependencies: @config_names',
+    $message = SafeMarkup::format('Configuration objects provided by %extension have unmet dependencies: %config_names',
       array(
-        '@config_names' => static::formatConfigObjectList($config_objects),
-        '@extension' => $extension
+        '%config_names' => static::formatConfigObjectList($config_objects),
+        '%extension' => $extension
       )
     );
     $e = new static($message);