Quote Originally Posted by mc12345678 View Post
In the attributes controller for the product, is the file upload attribute marked as required? (believe it is the red box on the right side of selections.)
It is indeed marked as required. Also that feature only prevents you from adding to cart if you didn't select a file to upload. Shopping_cart.php. Upload.php should be providing conditions (e.g. File extension) to shopping_cart.php.

I know my installation has many modules but none that would affect Shopping_cart.php file other than Canada post dimensions.