diff --git a/core/modules/auto_updates/tests/src/Build/UpdateTestBase.php b/core/modules/auto_updates/tests/src/Build/UpdateTestBase.php
index dae6215766f18470750c2ad6f3849776867fa594..8ef429977846dc114388eb587992dff0d4939833 100644
--- a/core/modules/auto_updates/tests/src/Build/UpdateTestBase.php
+++ b/core/modules/auto_updates/tests/src/Build/UpdateTestBase.php
@@ -32,14 +32,17 @@ protected function tearDown(): void {
   protected function createTestProject(string $template): void {
     parent::createTestProject($template);
 
+    // BEGIN: DELETE FROM CORE MERGE REQUEST
     // Install Automatic Updates into the test project and ensure it wasn't
     // symlinked.
-    $dir = 'project';
-    $this->runComposer('composer config repo.auto_updates path ' . __DIR__ . '/../../..', $dir);
-    $this->runComposer('composer require --no-update "drupal/auto_updates:@dev"', $dir);
-    $output = $this->runComposer('COMPOSER_MIRROR_PATH_REPOS=1 composer update --with-all-dependencies', $dir);
-    $this->assertStringNotContainsString('Symlinking', $output);
-
+    if (__NAMESPACE__ === 'Drupal\Tests\automatic_updates\Build') {
+      $dir = 'project';
+      $this->runComposer('composer config repo.automatic_updates path ' . __DIR__ . '/../../..', $dir);
+      $this->runComposer('composer require --no-update "drupal/automatic_updates:@dev"', $dir);
+      $output = $this->runComposer('COMPOSER_MIRROR_PATH_REPOS=1 composer update --with-all-dependencies', $dir);
+      $this->assertStringNotContainsString('Symlinking', $output);
+    }
+    // END: DELETE FROM CORE MERGE REQUEST
     // Install Drupal. Always allow test modules to be installed in the UI and,
     // for easier debugging, always display errors in their dubious glory.
     $this->installQuickStart('minimal');
@@ -128,7 +131,7 @@ protected function installModules(array $modules): void {
 
     $form_id = $assert_session->elementExists('css', 'input[type="hidden"][name="form_id"]')
       ->getValue();
-    if ($form_id === 'system_modules_confirm_form') {
+    if (preg_match('/^system_modules_(experimental_)?confirm_form$/', $form_id)) {
       $page->pressButton('Continue');
       $assert_session->statusCodeEquals(200);
     }
diff --git a/core/modules/auto_updates/tests/src/Kernel/ReadinessValidation/StagedDatabaseUpdateValidatorTest.php b/core/modules/auto_updates/tests/src/Kernel/ReadinessValidation/StagedDatabaseUpdateValidatorTest.php
index 1dbfdc399aaff5067c379f5bc7547b4561ded94c..11a90b4fa094ff1dc5dc40f8357e6b1e4bc7e8eb 100644
--- a/core/modules/auto_updates/tests/src/Kernel/ReadinessValidation/StagedDatabaseUpdateValidatorTest.php
+++ b/core/modules/auto_updates/tests/src/Kernel/ReadinessValidation/StagedDatabaseUpdateValidatorTest.php
@@ -164,7 +164,7 @@ public function testUpdatesAddedInStage(): void {
       // The file we're creating shouldn't already exist in the staging area
       // unless it's a file we actually ship, which is a scenario covered by
       // ::testFileChanged().
-      $this->assertFileNotExists($file);
+      $this->assertFileDoesNotExist($file);
       file_put_contents($file, $this->randomString());
     }
 
diff --git a/core/modules/help/tests/src/Kernel/HelpEmptyPageTest.php b/core/modules/help/tests/src/Kernel/HelpEmptyPageTest.php
index 663d168005f4eb4e22c1f5330d859d61f1cc008c..7a61d33c600268110a70c70f26ce9115a67c0867 100644
--- a/core/modules/help/tests/src/Kernel/HelpEmptyPageTest.php
+++ b/core/modules/help/tests/src/Kernel/HelpEmptyPageTest.php
@@ -17,7 +17,7 @@ class HelpEmptyPageTest extends KernelTestBase {
   /**
    * {@inheritdoc}
    */
-  protected static $modules = ['system', 'help_test', 'user', 'path_alias'];
+  protected static $modules = ['system', 'help_test', 'user', 'path_alias', 'package_manager'];
 
   /**
    * {@inheritdoc}
diff --git a/core/tests/Drupal/KernelTests/Core/Asset/ResolvedLibraryDefinitionsFilesMatchTest.php b/core/tests/Drupal/KernelTests/Core/Asset/ResolvedLibraryDefinitionsFilesMatchTest.php
index 026f8d32638685e2710410ccbfe6622e686709dc..fcdbeeddd5f87162227f2e7591e4ccc3ea79c557 100644
--- a/core/tests/Drupal/KernelTests/Core/Asset/ResolvedLibraryDefinitionsFilesMatchTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Asset/ResolvedLibraryDefinitionsFilesMatchTest.php
@@ -88,7 +88,7 @@ class ResolvedLibraryDefinitionsFilesMatchTest extends KernelTestBase {
   /**
    * {@inheritdoc}
    */
-  protected static $modules = ['system', 'user', 'path_alias'];
+  protected static $modules = ['system', 'user', 'path_alias', 'package_manager'];
 
   /**
    * {@inheritdoc}
@@ -132,6 +132,7 @@ protected function setUp(): void {
     $this->allModules[] = 'system';
     $this->allModules[] = 'user';
     $this->allModules[] = 'path_alias';
+    $this->allModules[] = 'package_manager';
     $database_module = \Drupal::database()->getProvider();
     if ($database_module !== 'core') {
       $this->allModules[] = $database_module;