diff --git a/phpBB/phpbb/install/installer.php b/phpBB/phpbb/install/installer.php
index a7d3b99dcb..e04e233a76 100644
--- a/phpBB/phpbb/install/installer.php
+++ b/phpBB/phpbb/install/installer.php
@@ -243,12 +243,18 @@ class installer
 			}
 			else
 			{
-				// Start session and try to apply session id
-				$auth = $this->container_factory->get('auth');
+				// Start session if not installing and get user object
+				// to allow redirecting to ACP
 				$user = $this->container_factory->get('user');
-				$user->session_begin();
-				$auth->acl($user->data);
-				$user->setup();
+				if (!isset($module) || !($module instanceof \phpbb\install\module\install_finish\module))
+				{
+					$auth = $this->container_factory->get('auth');
+
+					$user->session_begin();
+					$auth->acl($user->data);
+					$user->setup();
+				}
+
 				$phpbb_root_path = $this->container_factory->get_parameter('core.root_path');
 
 				$acp_url = append_sid($phpbb_root_path . 'adm/index.php', 'i=acp_help_phpbb&mode=help_phpbb', true, $user->session_id);