diff --git a/core/lib/Drupal/Core/Form/ConfigFormBase.php b/core/lib/Drupal/Core/Form/ConfigFormBase.php
index 83194fb58d..8f24090750 100644
--- a/core/lib/Drupal/Core/Form/ConfigFormBase.php
+++ b/core/lib/Drupal/Core/Form/ConfigFormBase.php
@@ -50,7 +50,7 @@ public function buildForm(array $form, FormStateInterface $form_state) {
         }
       }
       $text = Markup::create($text);
-      drupal_set_message(t("This form has values that are overridden either by a module or by settings files. <br /> You can still change them and they will be saved in the config storage, but the changes will maybe not appear within the site.<br />@overrides", ['@overrides' => $text] ), "warning");
+      drupal_set_message(t("This form has values that are overridden either by a module or by settings files. <br /> You can still change them and they will be saved in the config storage, but the changes will maybe not appear within the site.<br />@overrides", ['@overrides' => $text]), "warning");
     }
 
     $form['actions']['#type'] = 'actions';
diff --git a/core/lib/Drupal/Core/Form/ConfigFormBaseTrait.php b/core/lib/Drupal/Core/Form/ConfigFormBaseTrait.php
index 0764da2fe7..ddffb3ba34 100644
--- a/core/lib/Drupal/Core/Form/ConfigFormBaseTrait.php
+++ b/core/lib/Drupal/Core/Form/ConfigFormBaseTrait.php
@@ -68,7 +68,6 @@ protected function config($name) {
    *   the keys are multidimensional) and last the original string of the
    *   config, the value is the overridden string. Example:
    *   'system.site' => array('page.403' => array('original' => 'overridden'))
-   *
    */
   protected function getConfigOverrides() {
     /** @var \Drupal\Core\Config\ConfigFactoryInterface $config_factory */
@@ -87,16 +86,18 @@ protected function getConfigOverrides() {
     // Forms define which config objects they are using for editing, therefore
     // these are also the ones which can be overwritten.
     foreach ($this->getEditableConfigNames() as $name) {
-      // Loading the config with ->get() which means they are loaded overridden
+      // Loading the config with ->get() which means they are loaded overridden.
       $config = $config_factory->get($name);
 
       // Diff the overwritten with the original config, returns a diff with only
       // values that have overrides, others are removed.
-
-      $diff_overwritten = DiffArray::diffAssocRecursive($config->get(), $config->getOriginal('', FALSE));
+      if (!$config_values = $config->getOriginal('', FALSE)) {
+        continue;
+      }
+      $diff_overwritten = DiffArray::diffAssocRecursive($config->get(), $config_values);
       // We are also interested in the original strings, so we do the same on
-      // the oder side around.
-      $diff_original = DiffArray::diffAssocRecursive($config->getOriginal('', FALSE), $config->get());
+      // the other side around.
+      $diff_original = DiffArray::diffAssocRecursive($config_values, $config->get());
 
       // Config objects are multidimensional. Flatten them with the keys
       // concatenated with dots.
@@ -113,38 +114,40 @@ protected function getConfigOverrides() {
   }
 
   /**
-   * Flattens an nested array.
+   * Flattens a nested array.
    *
    * The scheme used is:
    *   'key' => array('key2' => array('key3' => 'value'))
    * Becomes:
    *   'key.key2.key3' => 'value'
    *
-   * This function takes an array by reference and will modify it
+   * This function takes an array by reference and will modify it.
    *
-   * @param array  &$messages The array that will be flattened
-   * @param array  $subnode   Current subnode being parsed, used internally for recursive calls
-   * @param string $path      Current path being parsed, used internally for recursive calls
+   * @param array &$messages
+   *   The array that will be flattened.
+   * @param array $subnode
+   *   Current subnode being parsed, used internally for recursive calls.
+   * @param string $path
+   *   Current path being parsed, used internally for recursive calls.
    */
-  private function flattenArray(array &$messages, array $subnode = null, $path = null)
-  {
-    if (null === $subnode) {
+  private function flattenArray(array &$messages, array $subnode = NULL, $path = NULL) {
+    if (NULL === $subnode) {
       $subnode = &$messages;
     }
     foreach ($subnode as $key => $value) {
       if (is_array($value)) {
-        $nodePath = $path ? $path.'.'.$key : $key;
-        $this->flattenArray($messages, $value, $nodePath);
-        if (null === $path) {
+        $node_path = $path ? $path . '.' . $key : $key;
+        $this->flattenArray($messages, $value, $node_path);
+        if (NULL === $path) {
           unset($messages[$key]);
         }
-      } elseif (null !== $path) {
-        $messages[$path.'.'.$key] = $value;
+      }
+      elseif (NULL !== $path) {
+        $messages[$path . '.' . $key] = $value;
       }
     }
   }
 
-
   /**
    * Gets the configuration names that will be editable.
    *