diff --git a/composer.lock b/composer.lock
index 468c7a6feb3..186f424dbd2 100644
--- a/composer.lock
+++ b/composer.lock
@@ -4,7 +4,7 @@
         "Read more about it at https://getcomposer.org/doc/01-basic-usage.md#installing-dependencies",
         "This file is @generated automatically"
     ],
-    "content-hash": "32af6ba7e80cd9503592966d1f071c63",
+    "content-hash": "5e658e150305bd8c42a49e766211d9c0",
     "packages": [
         {
             "name": "asm89/stack-cors",
@@ -534,7 +534,7 @@
             "dist": {
                 "type": "path",
                 "url": "core",
-                "reference": "874a51210b265aa07599dc966748e43cf31a0321"
+                "reference": "8d19de4587f2e384aad845327980c8793690bbc6"
             },
             "require": {
                 "asm89/stack-cors": "^1.1",
@@ -763,7 +763,6 @@
                     "lib/Drupal/Core/Site/Settings.php"
                 ],
                 "files": [
-                    "class_aliases.php",
                     "includes/bootstrap.inc"
                 ]
             },
diff --git a/core/class_aliases.php b/core/class_aliases.php
deleted file mode 100644
index f058962f842..00000000000
--- a/core/class_aliases.php
+++ /dev/null
@@ -1,12 +0,0 @@
-<?php
-
-/**
- * @file
- * Contains class_aliases that will be added by the autoloader.
- *
- * @see core/composer.json
- */
-
-// @todo https://www.drupal.org/project/drupal/issues/3197482 Remove this class
-//   alias once Drupal is running Symfony 5.3 or higher.
-class_alias('Drupal\Core\Http\KernelEvent', 'Symfony\Component\HttpKernel\Event\KernelEvent', TRUE);
diff --git a/core/composer.json b/core/composer.json
index b71a1889075..95e544cda25 100644
--- a/core/composer.json
+++ b/core/composer.json
@@ -202,7 +202,6 @@
             "lib/Drupal/Core/Site/Settings.php"
         ],
         "files": [
-            "class_aliases.php",
             "includes/bootstrap.inc"
         ]
     },
diff --git a/core/includes/bootstrap.inc b/core/includes/bootstrap.inc
index ca129be8275..f264cd364dc 100644
--- a/core/includes/bootstrap.inc
+++ b/core/includes/bootstrap.inc
@@ -123,6 +123,13 @@ define('REQUEST_TIME', (int) $_SERVER['REQUEST_TIME']);
  */
 define('DRUPAL_ROOT', dirname(__DIR__, 2));
 
+/**
+ * Declare class aliases that will be added by the autoloader.
+ */
+// @todo https://www.drupal.org/project/drupal/issues/3197482 Remove this class
+//   alias once Drupal is running Symfony 5.3 or higher.
+class_alias('Drupal\Core\Http\KernelEvent', 'Symfony\Component\HttpKernel\Event\KernelEvent', TRUE);
+
 /**
  * Returns and optionally sets the filename for a system resource.
  *