diff --git a/phpBB/phpbb/db/migration/data/v400/rename_duplicated_index_names.php b/phpBB/phpbb/db/migration/data/v400/rename_duplicated_index_names.php
index b4c10271e6..dc053a0f77 100644
--- a/phpBB/phpbb/db/migration/data/v400/rename_duplicated_index_names.php
+++ b/phpBB/phpbb/db/migration/data/v400/rename_duplicated_index_names.php
@@ -90,7 +90,7 @@ class rename_duplicated_index_names extends migration
 	public function get_tables_index_names()
 	{
 		$table_keys = [];
-		$schema_manager = $this->db_doctrine->createSchemaManager();
+		$schema_manager = $this->db_tools->get_connection()->createSchemaManager();
 		$table_names = $schema_manager->listTableNames();
 
 		if (!empty($table_names))
diff --git a/phpBB/phpbb/db/migration/migration.php b/phpBB/phpbb/db/migration/migration.php
index 63290229f9..6bfc395e4d 100644
--- a/phpBB/phpbb/db/migration/migration.php
+++ b/phpBB/phpbb/db/migration/migration.php
@@ -28,9 +28,6 @@ abstract class migration implements migration_interface
 	/** @var \phpbb\db\driver\driver_interface */
 	protected $db;
 
-	/** @var \Doctrine\DBAL\Connection */
-	protected $db_doctrine;
-
 	/** @var \phpbb\db\tools\tools_interface */
 	protected $db_tools;
 
@@ -75,9 +72,6 @@ abstract class migration implements migration_interface
 		$this->php_ext = $php_ext;
 
 		$this->errors = array();
-
-		$phpbb_config_php_file = new \phpbb\config_php_file($phpbb_root_path, $php_ext);
-		$this->db_doctrine = \phpbb\db\doctrine\connection_factory::get_connection($phpbb_config_php_file);
 	}
 
 	/**
diff --git a/phpBB/phpbb/db/tools/doctrine.php b/phpBB/phpbb/db/tools/doctrine.php
index 73987d26ee..f74f251712 100644
--- a/phpBB/phpbb/db/tools/doctrine.php
+++ b/phpBB/phpbb/db/tools/doctrine.php
@@ -61,6 +61,14 @@ class doctrine implements tools_interface
 		$this->connection = $connection;
 	}
 
+	/**
+	 * @return Connection
+	 */
+	public function get_connection(): Connection
+	{
+		return $this->connection;
+	}
+
 	/**
 	 * @return AbstractSchemaManager
 	 *