diff --git a/core/lib/Drupal/Core/Database/Connection.php b/core/lib/Drupal/Core/Database/Connection.php
index b502fdb..064adc2 100644
--- a/core/lib/Drupal/Core/Database/Connection.php
+++ b/core/lib/Drupal/Core/Database/Connection.php
@@ -1250,8 +1250,8 @@ public function quote($string, $parameter_type = \PDO::PARAM_STR) {
    */
   public function serialize() {
     $connection = clone $this;
-    // Don't serialize the PDO connection.
-    unset($connection->connection);
+    // Don't serialize the PDO connection and other lazy-instantiated members.
+    unset($connection->connection, $connection->schema, $connection->driverClasses);
     return serialize(get_object_vars($connection));
   }