1. We add the index.php because it does not display any content on frontend so just added index.php which includes admin/index.php
2. Database Upgrade is to be done only when the datbase version has changed in options table
3. We have tested since the versions in 2011 and there is no database change, so when there is database change in future please check auto upgrade properly
4. We copy the mod_upgrade.php for auto upgrade and then after auto upgrade we revert the original file orig_upgrade.php
if(empty($_POST['softlogin'])){
	yourls_maybe_require_auth();
}
5. PHP REQUIREMENT LINK : https://github.com/YOURLS/YOURLS/blob/master/readme.html#L534