diff --git a/core/lib/Drupal/Core/Session/MetadataBag.php b/core/lib/Drupal/Core/Session/MetadataBag.php
index ee0fbd4..e7a65a5 100644
--- a/core/lib/Drupal/Core/Session/MetadataBag.php
+++ b/core/lib/Drupal/Core/Session/MetadataBag.php
@@ -51,7 +51,9 @@ public function getCsrfTokenSeed() {
   /**
    * Clear the CSRF token seed.
    */
-  public function clearCsrfTokenSeed() {
+  public function stampNew($lifetime = null)
+  {
+    parent::stampNew($lifetime);
     unset($this->meta[static::CSRF_TOKEN_SEED]);
   }
 
diff --git a/core/lib/Drupal/Core/Session/SessionManager.php b/core/lib/Drupal/Core/Session/SessionManager.php
index 6071031..a51d301 100644
--- a/core/lib/Drupal/Core/Session/SessionManager.php
+++ b/core/lib/Drupal/Core/Session/SessionManager.php
@@ -119,17 +119,6 @@ public function start() {
     }
 
     if (empty($result)) {
-      // Randomly generate a session identifier for this request. This is
-      // necessary because \Drupal\Core\TempStore\SharedTempStoreFactory::get()
-      // wants to know the future session ID of a lazily started session in
-      // advance.
-      //
-      // @todo: With current versions of PHP there is little reason to generate
-      //   the session id from within application code. Consider using the
-      //   default php session id instead of generating a custom one:
-      //   https://www.drupal.org/node/2238561
-      $this->setId(Crypt::randomBytesBase64());
-
       // Initialize the session global and attach the Symfony session bags.
       $_SESSION = [];
       $this->loadSession();
@@ -210,30 +199,7 @@ public function regenerate($destroy = FALSE, $lifetime = NULL) {
       return;
     }
 
-    // We do not support the optional $destroy and $lifetime parameters as long
-    // as #2238561 remains open.
-    if ($destroy || isset($lifetime)) {
-      throw new \InvalidArgumentException('The optional parameters $destroy and $lifetime of SessionManager::regenerate() are not supported currently');
-    }
-
-    if ($this->isStarted()) {
-      $old_session_id = $this->getId();
-    }
-    session_id(Crypt::randomBytesBase64());
-
-    $this->getMetadataBag()->clearCsrfTokenSeed();
-
-    if (isset($old_session_id)) {
-      $params = session_get_cookie_params();
-      $expire = $params['lifetime'] ? REQUEST_TIME + $params['lifetime'] : 0;
-      setcookie($this->getName(), $this->getId(), $expire, $params['path'], $params['domain'], $params['secure'], $params['httponly']);
-      $this->migrateStoredSession($old_session_id);
-    }
-
-    if (!$this->isStarted()) {
-      // Start the session when it doesn't exist yet.
-      $this->startNow();
-    }
+    return parent::regenerate($destroy, $lifetime);
   }
 
   /**
@@ -324,18 +290,4 @@ protected function getSessionDataMask() {
     return array_intersect_key($mask, $_SESSION);
   }
 
-  /**
-   * Migrates the current session to a new session id.
-   *
-   * @param string $old_session_id
-   *   The old session ID. The new session ID is $this->getId().
-   */
-  protected function migrateStoredSession($old_session_id) {
-    $fields = ['sid' => Crypt::hashBase64($this->getId())];
-    $this->connection->update('sessions')
-      ->fields($fields)
-      ->condition('sid', Crypt::hashBase64($old_session_id))
-      ->execute();
-  }
-
 }
diff --git a/core/lib/Drupal/Core/TempStore/SharedTempStoreFactory.php b/core/lib/Drupal/Core/TempStore/SharedTempStoreFactory.php
index 90e816a..4267ede 100644
--- a/core/lib/Drupal/Core/TempStore/SharedTempStoreFactory.php
+++ b/core/lib/Drupal/Core/TempStore/SharedTempStoreFactory.php
@@ -2,6 +2,7 @@
 
 namespace Drupal\Core\TempStore;
 
+use Drupal\Component\Utility\Crypt;
 use Drupal\Core\KeyValueStore\KeyValueExpirableFactoryInterface;
 use Drupal\Core\Lock\LockBackendInterface;
 use Symfony\Component\HttpFoundation\RequestStack;
@@ -76,7 +77,20 @@ public function get($collection, $owner = NULL) {
     // Use the currently authenticated user ID or the active user ID unless
     // the owner is overridden.
     if (!isset($owner)) {
-      $owner = \Drupal::currentUser()->id() ?: session_id();
+      $account = \Drupal::currentUser();
+      $owner = $account->id();
+      if ($account->isAnonymous()) {
+        $has_session = $this->requestStack
+          ->getCurrentRequest()
+          ->hasSession();
+        if (!$has_session) {
+          /** @var \Symfony\Component\HttpFoundation\Session\SessionInterface $session */
+          $session = \Drupal::service('session');
+          $this->requestStack->getCurrentRequest()->setSession($session);
+          $session->start();
+        }
+        $owner = $this->requestStack->getCurrentRequest()->getSession()->getId();
+      }
     }
 
     // Store the data for this collection in the database.
diff --git a/core/modules/user/user.module b/core/modules/user/user.module
index b18408a..fae39a8 100644
--- a/core/modules/user/user.module
+++ b/core/modules/user/user.module
@@ -561,7 +561,7 @@ function user_login_finalize(UserInterface $account) {
   // This is called before hook_user_login() in case one of those functions
   // fails or incorrectly does a redirect which would leave the old session
   // in place.
-  \Drupal::service('session')->migrate();
+  \Drupal::service('session')->migrate(TRUE);
   \Drupal::service('session')->set('uid', $account->id());
   \Drupal::moduleHandler()->invokeAll('user_login', [$account]);
 }