diff -u b/core/modules/system/src/Tests/Installer/InstallerExistingConfigTestBase.php b/core/modules/system/src/Tests/Installer/InstallerExistingConfigTestBase.php
--- b/core/modules/system/src/Tests/Installer/InstallerExistingConfigTestBase.php
+++ b/core/modules/system/src/Tests/Installer/InstallerExistingConfigTestBase.php
@@ -32,6 +32,7 @@
       'type' => 'profile',
       'core' => \Drupal::CORE_COMPATIBILITY,
       'name' => 'Configuration installation test profile (' . $this->profile . ')',
+      'config_install' => TRUE,
     ];
     // File API functions are not available yet.
     $path = $this->siteDirectory . '/profiles/' . $this->profile;