diff -u b/core/lib/Drupal/Core/Render/Element/Details.php b/core/lib/Drupal/Core/Render/Element/Details.php
--- b/core/lib/Drupal/Core/Render/Element/Details.php
+++ b/core/lib/Drupal/Core/Render/Element/Details.php
@@ -94,7 +94,7 @@
$element['#attributes']['class'][] = 'details--child-error';
$element['#title'] = \Drupal::translation()->formatPlural(
count($element['#children_errors']),
- '@title (contains an error)',
+ '@title (contains error)',
'@title (contains @count errors)',
[
'@title' => $element['#title']
diff -u b/core/tests/Drupal/FunctionalJavascriptTests/Core/Render/Element/VerticalTabsTest.php b/core/tests/Drupal/FunctionalJavascriptTests/Core/Render/Element/VerticalTabsTest.php
--- b/core/tests/Drupal/FunctionalJavascriptTests/Core/Render/Element/VerticalTabsTest.php
+++ b/core/tests/Drupal/FunctionalJavascriptTests/Core/Render/Element/VerticalTabsTest.php
@@ -26,7 +26,7 @@
$this->submitForm([], 'Submit');
- $web_assert->elementTextContains('css', '.vertical-tabs__menu-item-title .child-error-indicator', '(contains an error)');
+ $web_assert->elementTextContains('css', '.vertical-tabs__menu-item-title .child-error-indicator', '(contains error)');
}
}