diff --git a/core/modules/block_content/tests/src/Functional/BlockContentTranslationUITest.php b/core/modules/block_content/tests/src/Functional/BlockContentTranslationUITest.php
index 3d93ed33e8546e2a582e03704e23e582ca5320b7..3f3fea1c26896028b1403d35ac6e3d0892df68e7 100644
--- a/core/modules/block_content/tests/src/Functional/BlockContentTranslationUITest.php
+++ b/core/modules/block_content/tests/src/Functional/BlockContentTranslationUITest.php
@@ -28,7 +28,7 @@ class BlockContentTranslationUITest extends ContentTranslationUITestBase {
   /**
    * {@inheritdoc}
    */
-  protected $defaultTheme = 'classy';
+  protected $defaultTheme = 'stark';
 
   /**
    * {@inheritdoc}
diff --git a/core/modules/content_translation/tests/src/Functional/ContentTestTranslationUITest.php b/core/modules/content_translation/tests/src/Functional/ContentTestTranslationUITest.php
index 3f644b9a8e5e8122f8c8f3c6cc7572165a41917a..ba0cbf67071da7c7967179c588aa17bf0e028e98 100644
--- a/core/modules/content_translation/tests/src/Functional/ContentTestTranslationUITest.php
+++ b/core/modules/content_translation/tests/src/Functional/ContentTestTranslationUITest.php
@@ -39,7 +39,7 @@ class ContentTestTranslationUITest extends ContentTranslationUITestBase {
   /**
    * {@inheritdoc}
    */
-  protected $defaultTheme = 'classy';
+  protected $defaultTheme = 'stark';
 
   /**
    * {@inheritdoc}
diff --git a/core/modules/content_translation/tests/src/Functional/ContentTranslationUITestBase.php b/core/modules/content_translation/tests/src/Functional/ContentTranslationUITestBase.php
index 776bd654ccdf0ac4b9df84f1d75d03e22b0216b2..e853e595df9d4eb02f64aec1f0fdbcdac94e9ea7 100644
--- a/core/modules/content_translation/tests/src/Functional/ContentTranslationUITestBase.php
+++ b/core/modules/content_translation/tests/src/Functional/ContentTranslationUITestBase.php
@@ -359,7 +359,7 @@ protected function doTestAuthoringInfo() {
     ];
     $this->drupalGet($entity->toUrl('edit-form'));
     $this->submitForm($edit, $this->getFormSubmitAction($entity, $langcode));
-    $this->assertSession()->elementExists('xpath', '//div[contains(@class, "error")]//ul');
+    $this->assertSession()->elementExists('xpath', '//div[@aria-label="Error message"]//ul');
     $metadata = $this->manager->getTranslationMetadata($entity->getTranslation($langcode));
     $this->assertEquals($values[$langcode]['uid'], $metadata->getAuthor()->id(), 'Translation author correctly kept.');
     $this->assertEquals($values[$langcode]['created'], $metadata->getCreatedTime(), 'Translation date correctly kept.');
diff --git a/core/modules/media/tests/src/Functional/MediaTranslationUITest.php b/core/modules/media/tests/src/Functional/MediaTranslationUITest.php
index 6b1d6442db0e85613259249599e405121524fd38..20d3cd8c6e2cce04819fa901d793e383092f56e0 100644
--- a/core/modules/media/tests/src/Functional/MediaTranslationUITest.php
+++ b/core/modules/media/tests/src/Functional/MediaTranslationUITest.php
@@ -17,7 +17,7 @@ class MediaTranslationUITest extends ContentTranslationUITestBase {
   /**
    * {@inheritdoc}
    */
-  protected $defaultTheme = 'classy';
+  protected $defaultTheme = 'stark';
 
   /**
    * {@inheritdoc}
diff --git a/core/modules/menu_link_content/tests/src/Functional/MenuLinkContentTranslationUITest.php b/core/modules/menu_link_content/tests/src/Functional/MenuLinkContentTranslationUITest.php
index a7ddeed92dd1bfb234d2174ea2656906b944b26d..8dc2b7865ed7d06ff28e044d455c7fb25819f015 100644
--- a/core/modules/menu_link_content/tests/src/Functional/MenuLinkContentTranslationUITest.php
+++ b/core/modules/menu_link_content/tests/src/Functional/MenuLinkContentTranslationUITest.php
@@ -32,7 +32,7 @@ class MenuLinkContentTranslationUITest extends ContentTranslationUITestBase {
   /**
    * {@inheritdoc}
    */
-  protected $defaultTheme = 'classy';
+  protected $defaultTheme = 'stark';
 
   /**
    * {@inheritdoc}
diff --git a/core/modules/shortcut/tests/src/Functional/ShortcutTranslationUITest.php b/core/modules/shortcut/tests/src/Functional/ShortcutTranslationUITest.php
index 0d0a80d6a53c6773dc545579dd87ef06b0aa619f..4b059fd0dbd46092708a3558ae1f68426511a7b5 100644
--- a/core/modules/shortcut/tests/src/Functional/ShortcutTranslationUITest.php
+++ b/core/modules/shortcut/tests/src/Functional/ShortcutTranslationUITest.php
@@ -35,7 +35,7 @@ class ShortcutTranslationUITest extends ContentTranslationUITestBase {
   /**
    * {@inheritdoc}
    */
-  protected $defaultTheme = 'classy';
+  protected $defaultTheme = 'stark';
 
   /**
    * {@inheritdoc}
diff --git a/core/modules/taxonomy/tests/src/Functional/TermTranslationUITest.php b/core/modules/taxonomy/tests/src/Functional/TermTranslationUITest.php
index 049da47d14838d437f35e8e8be5dcdbf503077c8..179b4adea871fd1493ab4c6cd7b3cb0840e16601 100644
--- a/core/modules/taxonomy/tests/src/Functional/TermTranslationUITest.php
+++ b/core/modules/taxonomy/tests/src/Functional/TermTranslationUITest.php
@@ -41,7 +41,7 @@ class TermTranslationUITest extends ContentTranslationUITestBase {
   /**
    * {@inheritdoc}
    */
-  protected $defaultTheme = 'classy';
+  protected $defaultTheme = 'stark';
 
   protected function setUp(): void {
     $this->entityTypeId = 'taxonomy_term';
diff --git a/core/modules/user/tests/src/Functional/UserTranslationUITest.php b/core/modules/user/tests/src/Functional/UserTranslationUITest.php
index 7ba1a2b9ec01f48b0c30a9495809299e4987f24f..9e7b2ea2489a8e011f17bdbdfbe3486a698e54eb 100644
--- a/core/modules/user/tests/src/Functional/UserTranslationUITest.php
+++ b/core/modules/user/tests/src/Functional/UserTranslationUITest.php
@@ -44,7 +44,7 @@ class UserTranslationUITest extends ContentTranslationUITestBase {
   /**
    * {@inheritdoc}
    */
-  protected $defaultTheme = 'classy';
+  protected $defaultTheme = 'stark';
 
   protected function setUp(): void {
     $this->entityTypeId = 'user';