diff --git a/core/lib/Drupal.php b/core/lib/Drupal.php
index 0b32dfa47c..c28293ab20 100644
--- a/core/lib/Drupal.php
+++ b/core/lib/Drupal.php
@@ -766,6 +766,7 @@ public static function time() {
    */
   public static function messenger() {
     // @todo Replace with service once LegacyMessenger is removed in 9.0.0.
+    // @see https://www.drupal.org/project/drupal/issues/2928994
     return new LegacyMessenger();
   }
 
diff --git a/core/lib/Drupal/Core/Messenger/LegacyMessenger.php b/core/lib/Drupal/Core/Messenger/LegacyMessenger.php
index 7969222489..856b557fbf 100644
--- a/core/lib/Drupal/Core/Messenger/LegacyMessenger.php
+++ b/core/lib/Drupal/Core/Messenger/LegacyMessenger.php
@@ -37,19 +37,6 @@ class LegacyMessenger implements MessengerInterface {
    */
   protected $messengerService;
 
-  /**
-   * LegacyMessenger constructor.
-   *
-   * @deprecated in Drupal 8.5.0 and will be removed before Drupal 9.0.0.
-   *   Use \Drupal\Core\Messenger\Messenger instead.
-   */
-  public function __construct() {
-    if (!isset($_SESSION['messages'])) {
-      $_SESSION['messages'] = [];
-    }
-    $this->messages = &$_SESSION['messages'];
-  }
-
   /**
    * {@inheritdoc}
    */
@@ -116,14 +103,14 @@ public function all() {
    *   The Messenger service.
    */
   public function getMessenger() {
-    // Use the Messenger service, if it exists. Note: because the container has
-    // the potential to be rebuilt during requests, this service cannot be
-    // directly stored on this class.
+    // Use the Messenger service, if it exists.
     if (\Drupal::hasService('messenger')) {
+      // Note: because the container has the potential to be rebuilt during
+      // requests, this service cannot be directly stored on this class.
       $messenger = \Drupal::service('messenger');
 
       // Transfer any messages into the service.
-      if ($this->messages) {
+      if (isset($this->messages)) {
         foreach ($this->messages as $type => $messages) {
           foreach ($messages as $message) {
             $messenger->addMessage($message, $type);
@@ -137,6 +124,19 @@ public function getMessenger() {
 
     // Otherwise, trigger an error.
     @trigger_error('Adding or retrieving messages prior to the container being initialized was deprecated in Drupal 8.5.0 and this functionality will be removed before Drupal 9.0.0. Please report this usage at https://www.drupal.org/node/2928994.', E_USER_DEPRECATED);
+
+    // Prematurely creating $_SESSION['messages'] in this class' constructor
+    // causes issues when the container attempts to initialize its own session
+    // later down the road. This can only be done after it has been determined
+    // the normal Messenger service is not available (i.e. no container) which
+    // is reasonable to assume that a new instance of this class will be
+    // created once the container becomes available.
+    if (!isset($_SESSION['messages'])) {
+      $_SESSION['messages'] = [];
+    }
+
+    // Reference the previous method core used to store messages.
+    $this->messages = &$_SESSION['messages'];
   }
 
   /**
diff --git a/core/tests/Drupal/KernelTests/Core/Messenger/MessengerTest.php b/core/tests/Drupal/KernelTests/Core/Messenger/MessengerTest.php
index c9b9258a6e..4bccb8b5a3 100644
--- a/core/tests/Drupal/KernelTests/Core/Messenger/MessengerTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Messenger/MessengerTest.php
@@ -2,7 +2,6 @@
 
 namespace Drupal\KernelTests\Core\Messenger;
 
-use Drupal\Core\Messenger\LegacyMessenger;
 use Drupal\Core\Messenger\Messenger;
 use Drupal\Core\Messenger\MessengerInterface;
 use Drupal\KernelTests\KernelTestBase;
@@ -37,7 +36,7 @@ public function testMessages() {
     $messenger->addMessage('Foobar');
     $messenger->addError('Foo');
 
-    // Verify that adding more messages by retrieving another instance works.
+    // Verify that retrieving another instance and adding more messages works.
     $messenger = \Drupal::messenger();
     $messenger->addStatus('Bar');
     $messenger->addWarning('Fiz');