diff --git a/core/modules/simpletest/src/InstallerTestBase.php b/core/modules/simpletest/src/InstallerTestBase.php
index 11e9076..c340c92 100644
--- a/core/modules/simpletest/src/InstallerTestBase.php
+++ b/core/modules/simpletest/src/InstallerTestBase.php
@@ -140,7 +140,7 @@ protected function setUp() {
 
     // Import new settings.php written by the installer.
     $request = Request::createFromGlobals();
-    $class_loader = require $this->container->get('app.root') . '/core/vendor/autoload.php';
+    $class_loader = require $this->container->get('app.root') . '/autoload.php';
     Settings::initialize($this->container->get('app.root'), DrupalKernel::findSitePath($request), $class_loader);
     foreach ($GLOBALS['config_directories'] as $type => $path) {
       $this->configDirectories[$type] = $path;
diff --git a/core/modules/simpletest/src/KernelTestBase.php b/core/modules/simpletest/src/KernelTestBase.php
index 14b839b..abc1f20 100644
--- a/core/modules/simpletest/src/KernelTestBase.php
+++ b/core/modules/simpletest/src/KernelTestBase.php
@@ -178,7 +178,7 @@ protected function setUp() {
     $GLOBALS['conf']['container_service_providers']['TestServiceProvider'] = 'Drupal\simpletest\TestServiceProvider';
 
     // Bootstrap a new kernel.
-    $class_loader = require DRUPAL_ROOT . '/core/vendor/autoload.php';
+    $class_loader = require DRUPAL_ROOT . '/autoload.php';
     $this->kernel = new DrupalKernel('testing', $class_loader, FALSE);
     $request = Request::create('/');
     $site_path = DrupalKernel::findSitePath($request);
diff --git a/core/modules/simpletest/src/WebTestBase.php b/core/modules/simpletest/src/WebTestBase.php
index 63cf76a..7088456 100644
--- a/core/modules/simpletest/src/WebTestBase.php
+++ b/core/modules/simpletest/src/WebTestBase.php
@@ -862,7 +862,7 @@ protected function setUp() {
     // Since Drupal is bootstrapped already, install_begin_request() will not
     // bootstrap again. Hence, we have to reload the newly written custom
     // settings.php manually.
-    $class_loader = require DRUPAL_ROOT . '/core/vendor/autoload.php';
+    $class_loader = require DRUPAL_ROOT . '/autoload.php';
     Settings::initialize(DRUPAL_ROOT, $this->siteDirectory, $class_loader);
 
     // Execute the non-interactive installer.
diff --git a/core/modules/system/src/Tests/DrupalKernel/DrupalKernelTest.php b/core/modules/system/src/Tests/DrupalKernel/DrupalKernelTest.php
index ebd8307..03e56fc 100644
--- a/core/modules/system/src/Tests/DrupalKernel/DrupalKernelTest.php
+++ b/core/modules/system/src/Tests/DrupalKernel/DrupalKernelTest.php
@@ -61,7 +61,7 @@ protected function prepareConfigDirectories() {
    */
   protected function getTestKernel(Request $request, array $modules_enabled = NULL, $read_only = FALSE) {
     // Manually create kernel to avoid replacing settings.
-    $class_loader = require DRUPAL_ROOT . '/core/vendor/autoload.php';
+    $class_loader = require DRUPAL_ROOT . '/autoload.php';
     $kernel = DrupalKernel::createFromRequest($request, $class_loader, 'testing');
     $this->settingsSet('container_yamls', []);
     $this->settingsSet('hash_salt', $this->databasePrefix);
@@ -168,7 +168,7 @@ public function testCompileDIC() {
    */
   public function testRepeatedBootWithDifferentEnvironment() {
     $request = Request::createFromGlobals();
-    $class_loader = require DRUPAL_ROOT . '/core/vendor/autoload.php';
+    $class_loader = require DRUPAL_ROOT . '/autoload.php';
 
     $environments = [
       'testing1',
diff --git a/core/modules/system/src/Tests/System/IgnoreReplicaSubscriberTest.php b/core/modules/system/src/Tests/System/IgnoreReplicaSubscriberTest.php
index 3615c43..18298f9 100644
--- a/core/modules/system/src/Tests/System/IgnoreReplicaSubscriberTest.php
+++ b/core/modules/system/src/Tests/System/IgnoreReplicaSubscriberTest.php
@@ -32,7 +32,7 @@ function testSystemInitIgnoresSecondaries() {
     Database::addConnectionInfo('default', 'replica', $connection_info['default']);
 
     db_ignore_replica();
-    $class_loader = require \Drupal::root() . '/core/vendor/autoload.php';
+    $class_loader = require \Drupal::root() . '/autoload.php';
     $kernel = new DrupalKernel('testing', $class_loader, FALSE);
     $event = new GetResponseEvent($kernel, Request::create('http://example.com'), HttpKernelInterface::MASTER_REQUEST);
     $subscriber = new ReplicaDatabaseIgnoreSubscriber();
diff --git a/core/scripts/migrate-dump-d6.sh b/core/scripts/migrate-dump-d6.sh
index 11e05c5..6d9b366 100755
--- a/core/scripts/migrate-dump-d6.sh
+++ b/core/scripts/migrate-dump-d6.sh
@@ -29,7 +29,7 @@
   return;
 }
 
-$autoloader  = require __DIR__ . '/../vendor/autoload.php';
+$autoloader  = require __DIR__ . '/../../autoload.php';
 require_once __DIR__ . '/../includes/bootstrap.inc';
 
 $request = Request::createFromGlobals();
diff --git a/core/scripts/password-hash.sh b/core/scripts/password-hash.sh
index b1cfa2f..cf5e9e3 100755
--- a/core/scripts/password-hash.sh
+++ b/core/scripts/password-hash.sh
@@ -55,7 +55,7 @@
 // Password list to be processed.
 $passwords = $_SERVER['argv'];
 
-$autoloader = require __DIR__ . '/../vendor/autoload.php';
+$autoloader = require __DIR__ . '/../../autoload.php';
 
 $request = Request::createFromGlobals();
 $kernel = DrupalKernel::createFromRequest($request, $autoloader, 'prod', FALSE);
diff --git a/core/scripts/rebuild_token_calculator.sh b/core/scripts/rebuild_token_calculator.sh
index 87c3069..38a64ab 100755
--- a/core/scripts/rebuild_token_calculator.sh
+++ b/core/scripts/rebuild_token_calculator.sh
@@ -15,7 +15,7 @@
   return;
 }
 
-require __DIR__ . '/../vendor/autoload.php';
+require __DIR__ . '/../../autoload.php';
 require_once __DIR__ . '/../includes/bootstrap.inc';
 
 $request = Request::createFromGlobals();
diff --git a/core/tests/bootstrap.php b/core/tests/bootstrap.php
index 76f745c..d0512e1 100644
--- a/core/tests/bootstrap.php
+++ b/core/tests/bootstrap.php
@@ -68,7 +68,7 @@ function drupal_phpunit_register_extension_dirs(Composer\Autoload\ClassLoader $l
 }
 
 // Start with classes in known locations.
-$loader = require __DIR__ . '/../vendor/autoload.php';
+$loader = require __DIR__ . '/../../autoload.php';
 $loader->add('Drupal\\Tests', __DIR__);
 
 // Scan for arbitrary extension namespaces from core and contrib.