diff --git a/core/includes/session.inc b/core/includes/session.inc
index e29216a..bd77cdc 100644
--- a/core/includes/session.inc
+++ b/core/includes/session.inc
@@ -7,14 +7,12 @@
 
 use Drupal\Component\Utility\Crypt;
 use Drupal\Core\Session\SessionHandler;
-use Drupal\Core\Session\UserSession;
 use Drupal\Core\Utility\Error;
 
 /**
  * Initializes the session handler, starting a session if needed.
  */
 function drupal_session_initialize() {
-  /** @var UserSession $user */
   global $user;
 
   if (drupal_is_cli()) {
@@ -86,7 +84,6 @@ function drupal_session_start() {
  * If an anonymous user already have an empty session, destroy it.
  */
 function drupal_session_commit() {
-  /** @var UserSession $user */
   global $user;
 
   if (!drupal_save_session() || drupal_is_cli()) {
@@ -94,7 +91,7 @@ function drupal_session_commit() {
     return;
   }
 
-  if ($user->isAnonymous() && empty($_SESSION)) {
+  if ($user && $user->isAnonymous() && empty($_SESSION)) {
     // There is no session data to store, destroy the session if it was
     // previously started.
     if (drupal_session_started()) {
@@ -127,7 +124,7 @@ function drupal_session_started($set = NULL) {
   if (isset($set)) {
     $session_started = $set;
   }
-  return $session_started && \PHP_SESSION_ACTIVE === session_status();
+  return $session_started && session_status() === \PHP_SESSION_ACTIVE;
 }
 
 /**
diff --git a/core/lib/Drupal/Core/Authentication/Provider/Cookie.php b/core/lib/Drupal/Core/Authentication/Provider/Cookie.php
index 7c6c5fb..ae108dc 100644
--- a/core/lib/Drupal/Core/Authentication/Provider/Cookie.php
+++ b/core/lib/Drupal/Core/Authentication/Provider/Cookie.php
@@ -44,7 +44,7 @@ public function authenticate(Request $request) {
    * {@inheritdoc}
    */
   public function cleanup(Request $request) {
-    drupal_session_commit(); #
+    drupal_session_commit();
   }
 
   /**
diff --git a/core/lib/Drupal/Core/Session/SessionHandler.php b/core/lib/Drupal/Core/Session/SessionHandler.php
index 97ff354..80adf12 100644
--- a/core/lib/Drupal/Core/Session/SessionHandler.php
+++ b/core/lib/Drupal/Core/Session/SessionHandler.php
@@ -34,6 +34,13 @@ class SessionHandler implements \SessionHandlerInterface, DestructableInterface
   protected $connection;
 
   /**
+   * An array containing the sid and data from last read.
+   *
+   * @var array
+   */
+  protected $lastRead;
+
+  /**
    * Constructs a new SessionHandler instance.
    *
    * @param \Symfony\Component\HttpFoundation\Request $request
@@ -118,9 +125,8 @@ public function read($sid) {
       $user = new UserSession();
     }
 
-    // Store the session that was read for comparison in _drupal_session_write().
-    $last_read = &drupal_static('drupal_session_last_read');
-    $last_read = array(
+    // Store the session that was read for comparison in self::write().
+    $this->lastRead = array(
       'sid' => $sid,
       'value' => $user->session,
     );
@@ -141,8 +147,7 @@ public function write($sid, $value) {
         return TRUE;
       }
       // Check whether $_SESSION has been changed in this request.
-      $last_read = &drupal_static('drupal_session_last_read');
-      $is_changed = !isset($last_read) || $last_read['sid'] != $sid || $last_read['value'] !== $value;
+      $is_changed = empty($this->lastRead) || $this->lastRead['sid'] != $sid || $this->lastRead['value'] !== $value;
 
       // For performance reasons, do not update the sessions table, unless
       // $_SESSION has changed or more than 180 has passed since the last update.