In Build 969 the new language file root/language/acp/permissions_phpbb.php is missing:

// Forum Permissions
$lang = array_merge($lang, array(
'ACL_F_LIST' => 'Can see forum',
'ACL_F_READ' => 'Can read forum',

please look here https://area51.phpbb.com/phpBB/viewtopic.php?f=108&t=44285#p254947

As more missing