Quote Originally Posted by thehighlandsgroup View Post
I've installed Stock by Attribute Module Version 4.6 and am running ZenCart Version 1.3.7 . After running SQL file. The admin portion of store is running correctly but customers are not able to check out they get the following error upon checkout:

Fatal error: Cannot redeclare class order in /var/www/vhosts/kasmarpro.com/httpdocs/smokejumpers/includes/classes/order.php on line 20
This error is one of the less opaque that PHP gives and means exactly what it says, that your site is trying to declare the same class twice.

Most likely this is because when you uploaded the stock by attribute mod you, or your FTP program, made a backup of the order.php class in the location quoted and left it there. Zen Cart can't tell the difference between files that are intended as backups and ones that it is supposed to load, so tries to load the same class twice.