core/includes/theme.inc                                | 1 -
 core/modules/system/system.module                      | 1 -
 core/themes/bartik/templates/status-messages.html.twig | 2 --
 core/themes/classy/templates/system/page.html.twig     | 1 +
 4 files changed, 1 insertion(+), 4 deletions(-)

diff --git a/core/includes/theme.inc b/core/includes/theme.inc
index 9e4ed90..2b7b5d2 100644
--- a/core/includes/theme.inc
+++ b/core/includes/theme.inc
@@ -1741,7 +1741,6 @@ function drupal_common_theme() {
     ),
     'status_messages' => array(
       'variables' => ['status_headings' => [], 'message_list' => NULL],
-      'template' => 'status-messages',
     ),
     'links' => array(
       'variables' => array('links' => array(), 'attributes' => array('class' => array('links')), 'heading' => array(), 'set_active_class' => FALSE),
diff --git a/core/modules/system/system.module b/core/modules/system/system.module
index c8552bc..d73ba63 100644
--- a/core/modules/system/system.module
+++ b/core/modules/system/system.module
@@ -170,7 +170,6 @@ function system_theme() {
     ),
     'block__system_messages_block' => array(
       'base hook' => 'block',
-      'template' => 'block--system-messages-block',
     ),
     'block__system_menu_block' => array(
       'render element' => 'elements',
diff --git a/core/themes/bartik/templates/status-messages.html.twig b/core/themes/bartik/templates/status-messages.html.twig
index be6431e..eb84273 100644
--- a/core/themes/bartik/templates/status-messages.html.twig
+++ b/core/themes/bartik/templates/status-messages.html.twig
@@ -20,8 +20,6 @@
  *   displaying messages of that specific type.
  *
  * @see template_preprocess_status_messages()
- *
- * @ingroup themeable
  */
 #}
 {% block messages %}
diff --git a/core/themes/classy/templates/system/page.html.twig b/core/themes/classy/templates/system/page.html.twig
index 72ebdcc..437a11c 100644
--- a/core/themes/classy/templates/system/page.html.twig
+++ b/core/themes/classy/templates/system/page.html.twig
@@ -42,6 +42,7 @@
  *
  * Regions:
  * - page.header: Items for the header region.
+ * - page.messages: Status and error messages. Should be displayed prominently.
  * - page.primary_menu: Items for the primary menu region.
  * - page.secondary_menu: Items for the secondary menu region.
  * - page.highlighted: Items for the highlighted content region.