diff --git a/core/includes/theme.inc.rej b/core/includes/theme.inc.rej
deleted file mode 100644
index a2c1811..0000000
--- a/core/includes/theme.inc.rej
+++ /dev/null
@@ -1,14 +0,0 @@
-diff a/core/includes/theme.inc b/core/includes/theme.inc	(rejected hunks)
-@@ -1146,6 +1146,12 @@ function template_preprocess_container(&$variables) {
- 
-   $variables['children'] = $element['#children'];
-   $variables['attributes'] = $element['#attributes'];
-+
-+  // Display any error messages.
-+  $variables['errors'] = NULL;
-+  if (!empty($element['#errors']) && empty($element['#error_no_message'])) {
-+   $variables['errors'] = $element['#errors'];
-+  }
- }
- 
- /**
diff --git a/core/modules/system/src/Tests/Form/ElementTest.php b/core/modules/system/src/Tests/Form/ElementTest.php
index 684e13a..0ff443f 100644
--- a/core/modules/system/src/Tests/Form/ElementTest.php
+++ b/core/modules/system/src/Tests/Form/ElementTest.php
@@ -162,11 +162,18 @@ public function testFormAutocomplete() {
   }
 
   /**
-   * Tests form element error messages.
+   * Tests form details element error messages.
    */
-  public function testFormElementErrors() {
+  public function testFormDetailsErrors() {
     $this->drupalPostForm('form_test/details-form', [], 'Submit');
     $this->assertText('I am an error on the details element.');
   }
+  /**
+   * Tests form container element error messages.
+   */
+  public function testFormElementErrors() {
+    $this->drupalPostForm('form_test/container-form', [], 'Submit');
+    $this->assertText('I am an error on the container element.');
+  }
 
 }
diff --git a/core/modules/system/templates/container.html.twig.rej b/core/modules/system/templates/container.html.twig.rej
deleted file mode 100644
index 9f64af5..0000000
--- a/core/modules/system/templates/container.html.twig.rej
+++ /dev/null
@@ -1,22 +0,0 @@
-diff a/core/modules/system/templates/container.html.twig b/core/modules/system/templates/container.html.twig	(rejected hunks)
-@@ -12,6 +12,7 @@
-  *
-  * Available variables:
-  * - attributes: HTML attributes for the containing element.
-+ * - errors: (optional) Any errors for this container element, may not be set.
-  * - children: The rendered child elements of the container.
-  * - has_parent: A flag to indicate that the container has one or more parent
-      containers.
-@@ -27,4 +28,11 @@
-     has_parent ? 'form-wrapper',
-   ]
- %}
--<div{{ attributes.addClass(classes) }}>{{ children }}</div>
-+<div{{ attributes.addClass(classes) }}>
-+{% if errors %}
-+  <div>
-+    {{ errors }}
-+  </div>
-+{% endif %}
-+{{ children }}
-+</div>
diff --git a/core/modules/system/tests/modules/form_test/form_test.routing.yml b/core/modules/system/tests/modules/form_test/form_test.routing.yml
index 42a6ba4..327d7fd 100644
--- a/core/modules/system/tests/modules/form_test/form_test.routing.yml
+++ b/core/modules/system/tests/modules/form_test/form_test.routing.yml
@@ -409,6 +409,14 @@ form_test.details_form:
   requirements:
     _access: 'TRUE'
 
+form_test.container_form:
+  path: '/form_test/container-form'
+  defaults:
+    _form: '\Drupal\form_test\Form\FormTestContainerForm'
+    _title: 'Form contaner form test'
+  requirements:
+    _access: 'TRUE'
+
 form_test.description_display:
   path: '/form_test/form-descriptions'
   defaults:
diff --git a/core/modules/system/tests/modules/form_test/src/Form/FormTestDetailsForm.php b/core/modules/system/tests/modules/form_test/src/Form/FormTestDetailsForm.php
index 5949679..55fcbfd 100644
--- a/core/modules/system/tests/modules/form_test/src/Form/FormTestDetailsForm.php
+++ b/core/modules/system/tests/modules/form_test/src/Form/FormTestDetailsForm.php
@@ -6,7 +6,7 @@
 use Drupal\Core\Form\FormStateInterface;
 
 /**
- * Builds a simple form to test the #group property on #type 'container'.
+ * Builds a simple form to test the #group property on #type 'details'.
  */
 class FormTestDetailsForm extends FormBase {
 
diff --git a/core/themes/classy/templates/form/container.html.twig.rej b/core/themes/classy/templates/form/container.html.twig.rej
deleted file mode 100644
index db1ca62..0000000
--- a/core/themes/classy/templates/form/container.html.twig.rej
+++ /dev/null
@@ -1,22 +0,0 @@
-diff a/core/themes/classy/templates/form/container.html.twig b/core/themes/classy/templates/form/container.html.twig	(rejected hunks)
-@@ -12,6 +12,7 @@
-  *
-  * Available variables:
-  * - attributes: HTML attributes for the containing element.
-+ * - errors: (optional) Any errors for this container element, may not be set.
-  * - children: The rendered child elements of the container.
-  * - has_parent: A flag to indicate that the container has one or more parent
-      containers.
-@@ -25,4 +26,11 @@
-     has_parent ? 'form-wrapper',
-   ]
- %}
--<div{{ attributes.addClass(classes) }}>{{ children }}</div>
-+<div{{ attributes.addClass(classes) }}>
-+{% if errors %}
-+  <div class="form-item--error-message">
-+    <strong>{{ errors }}</strong>
-+  </div>
-+{% endif %}
-+{{ children }}
-+</div>