diff -u b/core/lib/Drupal/Core/DependencyInjection/Compiler/BackendCompilerPass.php b/core/lib/Drupal/Core/DependencyInjection/Compiler/BackendCompilerPass.php
--- b/core/lib/Drupal/Core/DependencyInjection/Compiler/BackendCompilerPass.php
+++ b/core/lib/Drupal/Core/DependencyInjection/Compiler/BackendCompilerPass.php
@@ -52,6 +52,7 @@
     else {
       try {
         $default_backend = $container->get('database')->driver();
+        $container->set('database', NULL);
       }
       catch (\Exception $e) {
         // If Drupal is not installed or a test doesn't define database there