Regarding all the complaints about upgrading...
Upgrading is a complex operation, which cannot be performed without additional adjustments if the X-Cart store being upgraded contains some customized files that are affected by the patch. Even if you have a fresh 4.1.3 you can get some difficulties because of issues that might arise while unpacking the upgrade patch (e.g. see
http://forum.x-cart.com/showthread.php?p=148672#post148672).
All I can advise here is follow the instructions in the README file of the upgrade pack very carefully. If, nevertheless, you cannot do the upgrade, contact our support team.
Thank you.