diff --git a/core/lib/Drupal/Core/Database/Connection.php b/core/lib/Drupal/Core/Database/Connection.php
index 7d12118..b502fdb 100644
--- a/core/lib/Drupal/Core/Database/Connection.php
+++ b/core/lib/Drupal/Core/Database/Connection.php
@@ -1249,19 +1249,22 @@ public function quote($string, $parameter_type = \PDO::PARAM_STR) {
    * {@inheritdoc}
    */
   public function serialize() {
-    // Just store the target and the key of the connection because this is all
-    // what drupal needs to get a proper connection running again.
-    return serialize(array($this->target, $this->key));
+    $connection = clone $this;
+    // Don't serialize the PDO connection.
+    unset($connection->connection);
+    return serialize(get_object_vars($connection));
   }
 
   /**
    * {@inheritdoc}
    */
   public function unserialize($serialized) {
-    list($target, $key) = unserialize($serialized);
-    foreach (get_object_vars(Database::getConnection($target, $key)) as $name => $value) {
-      $this->{$name} = $value;
+    $data = unserialize($serialized);
+    foreach ($data as $key => $value) {
+      $this->{$key} = $value;
     }
+    // Re-establish the PDO connection using the original options.
+    $this->connection = static::open($this->connectionOptions);
   }
 
 }
diff --git a/core/modules/system/lib/Drupal/system/Tests/Database/ConnectionTest.php b/core/modules/system/lib/Drupal/system/Tests/Database/ConnectionTest.php
index 18f4c86..85e6aef 100644
--- a/core/modules/system/lib/Drupal/system/Tests/Database/ConnectionTest.php
+++ b/core/modules/system/lib/Drupal/system/Tests/Database/ConnectionTest.php
@@ -130,9 +130,15 @@ function testConnectionOptions() {
   public function testConnectionSerialization() {
     $db = Database::getConnection('default', 'default');
 
-    $serialized = serialize($db);
-    $unserialized = unserialize($serialized);
-
-    $this->assertIdenticalObject($db, $unserialized, 'Serializing and unserializing a connection returns an identical object.');
+    try {
+      $serialized = serialize($db);
+      $this->pass('The database connection can be serialized.');
+
+      $unserialized = unserialize($serialized);
+      $this->assertTrue(get_class($unserialized) === get_class($db));
+    }
+    catch (\Exception $e) {
+      $this->fail('The database connection cannot be serialized.');
+    }
   }
 }
diff --git a/core/modules/system/lib/Drupal/system/Tests/Form/FormTest.php b/core/modules/system/lib/Drupal/system/Tests/Form/FormTest.php
index ef498e1..f402395 100644
--- a/core/modules/system/lib/Drupal/system/Tests/Form/FormTest.php
+++ b/core/modules/system/lib/Drupal/system/Tests/Form/FormTest.php
@@ -669,8 +669,8 @@ function testMultiFormSameNameErrorClass() {
    * Tests a form with a form state storing a database connection.
    */
   public function testFormStateDatabaseConnection() {
-    $this->assertNoText(t('Database connection found'));
+    $this->assertNoText('Database connection found');
     $this->drupalPost('form-test/form_state-database', array(), t('Submit'));
-    $this->assertText(t('Database connection found'));
+    $this->assertText('Database connection found');
   }
 }
diff --git a/core/modules/system/tests/modules/form_test/form_test.module b/core/modules/system/tests/modules/form_test/form_test.module
index afcc3f9..97657a1 100644
--- a/core/modules/system/tests/modules/form_test/form_test.module
+++ b/core/modules/system/tests/modules/form_test/form_test.module
@@ -2480,7 +2480,6 @@ function form_test_group_vertical_tabs() {
  * Builds a form which gets the database connection stored in the form state.
  */
 function form_test_form_state_database($form, &$form_state) {
-
   $form['text'] = array(
     '#type' => 'textfield',
     '#title' => t('Text field'),
@@ -2491,11 +2490,12 @@ function form_test_form_state_database($form, &$form_state) {
     '#value' => t('Submit'),
   );
 
-  if (!isset($form_state['storage']['database'])) {
-    $form_state['storage']['database'] = Database::getConnection('default');
-  }
-  elseif ($form_state['storage']['database'] instanceof Connection) {
-    $form['database']['#markup'] = t('Database connection found');
+  $db = Database::getConnection('default');
+  $form_state['storage']['database'] = $db;
+  $form_state['storage']['database_class'] = get_class($db);
+
+  if (isset($form_state['storage']['database_connection_found'])) {
+    $form['database']['#markup'] = 'Database connection found';
   }
 
   return $form;
@@ -2506,5 +2506,9 @@ function form_test_form_state_database($form, &$form_state) {
  */
 function form_test_form_state_database_submit($form, &$form_state) {
   $form_state['cache'] = TRUE;
-  $form_state['rebuild'] = FALSE;
+  $form_state['rebuild'] = TRUE;
+
+  if ($form_state['storage']['database'] instanceof $form_state['storage']['database_class']) {
+    $form_state['storage']['database_connection_found'] = TRUE;
+  }
 }