Description
When the option "Use Ajax to add products" is activated and some products are added to cart from basket page (via recommended block or special offer) changing quantity in the basket causes the layout breaks and the error:
Block doesn't exist:block_cart
 
Solution
http://www.viart.com/downloads/5.block_basket.html.zip
 
Download the file above and extract 'block_basket.html' in the 'templates/user' folder replacing existing file. Please do not forget to make a backup copy of the current file in case something goes wrong.