diff --git a/phpBB/phpbb/composer/installer.php b/phpBB/phpbb/composer/installer.php
index 3a03e29ef5..1bc2c8e6b4 100644
--- a/phpBB/phpbb/composer/installer.php
+++ b/phpBB/phpbb/composer/installer.php
@@ -471,13 +471,18 @@ class installer
 		$composer = Factory::create($io, null, false);
 
 		$core_packages = $this->get_core_packages($composer);
+
+		// The composer/installers package must be installed on his own and not provided by the existing autoloader
+		$core_replace = $core_packages;
+		unset($core_replace['composer/installers']);
+
 		$ext_json_data = [
 			'require' => array_merge(
 				['php' => $this->get_core_php_requirement($composer)],
 				$core_packages,
 				$this->get_extra_dependencies(),
 				$packages),
-			'replace' => $core_packages,
+			'replace' => $core_replace,
 			'repositories' => $this->get_composer_repositories(),
 			'config' => [
 				'vendor-dir'=> $this->packages_vendor_dir,
diff --git a/phpBB/phpbb/db/migration/data/v330/extensions_composer_2.php b/phpBB/phpbb/db/migration/data/v330/extensions_composer_2.php
new file mode 100644
index 0000000000..c6ea7f4c13
--- /dev/null
+++ b/phpBB/phpbb/db/migration/data/v330/extensions_composer_2.php
@@ -0,0 +1,33 @@
+<?php
+/**
+*
+* This file is part of the phpBB Forum Software package.
+*
+* @copyright (c) phpBB Limited <https://www.phpbb.com>
+* @license GNU General Public License, version 2 (GPL-2.0)
+*
+* For full copyright and license information, please see
+* the docs/CREDITS.txt file.
+*
+*/
+
+namespace phpbb\db\migration\data\v330;
+
+class extensions_composer_2 extends \phpbb\db\migration\migration
+{
+	public function update_data()
+	{
+		$repositories = json_decode($this->config('exts_composer_repositories'), true);
+		$repositories[] = 'https://satis.phpbb.com';
+		$repositories = array_unique($repositories);
+
+		return array(
+			array('config.update', array('exts_composer_repositories', json_encode($repositories, JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES))),
+		);
+	}
+
+	static public function depends_on()
+	{
+		return array('\phpbb\db\migration\data\v330\extensions_composer');
+	}
+}