diff -u b/core/lib/Drupal/Core/Site/Settings.php b/core/lib/Drupal/Core/Site/Settings.php
--- b/core/lib/Drupal/Core/Site/Settings.php
+++ b/core/lib/Drupal/Core/Site/Settings.php
@@ -50,7 +50,7 @@
    */
   public static function getInstance() {
     if (self::$instance === NULL) {
-      throw new \BadMethodCallException('Whatever you are trying to do, it might be too early for that. You could call Settings::initialize(), but it is probably better to wait until it is called in the regular way. Also check for recursions.');
+      throw new \BadMethodCallException('Settings::$instance is not initialized yet. Whatever you are trying to do, it might be too early for that. You could call Settings::initialize(), but it is probably better to wait until it is called in the regular way. Also check for recursions.');
     }
     return self::$instance;
   }