diff -u b/core/includes/config.inc b/core/includes/config.inc
--- b/core/includes/config.inc
+++ b/core/includes/config.inc
@@ -35,11 +35,11 @@
     $default_storage = new FileStorage($config_dir);
     $other_module_config = array_filter($default_storage->listAll(),
       function ($value) use ($name) {
-        return !preg_match('/^'.$name.'\./', $value);
+        return !preg_match('/^' . $name . '\./', $value);
       }
     );
     $enabled_extensions = array_keys(\Drupal::moduleHandler()->getModuleList());
-    $enabled_extensions +=  array_keys(array_filter(list_themes(), function ($theme) {return $theme->status;}));
+    $enabled_extensions += array_keys(array_filter(list_themes(), function ($theme) {return $theme->status;}));
 
     $other_module_config = array_filter($other_module_config, function ($config_name) use ($enabled_extensions) {
       $provider = Unicode::substr($config_name,0, strpos($config_name, '.'));
diff -u b/core/modules/config/lib/Drupal/config/Tests/ConfigCRUDTest.php b/core/modules/config/lib/Drupal/config/Tests/ConfigCRUDTest.php
--- b/core/modules/config/lib/Drupal/config/Tests/ConfigCRUDTest.php
+++ b/core/modules/config/lib/Drupal/config/Tests/ConfigCRUDTest.php
@@ -182,19 +182,6 @@
       $this->fail($message);
     }
 
-    // This is now impossible since we search default configuration directories
-    // for the name plus a period.
-//    // Verify an exception is thrown when importing configuration with an
-//    // invalid name (missing a namespace).
-//    $message = 'Expected ConfigNameException was thrown when attempting to install invalid configuration.';
-//    try {
-//      $this->enableModules(array('config_test_invalid_name'));
-//      $this->installConfig(array('config_test_invalid_name'));
-//      $this->fail($message);
-//    }
-//    catch (ConfigNameException $e) {
-//      $this->pass($message);
-//    }
   }
 }