When customers select Proceed to Checkout their cart is emptied
When I began using Magento 9 months ago on our live website, our customer service department occasionally would get emails or phone calls about people having trouble checking out. We spent months trying to determine the cause of this issue without much success.
The problem was as follows: A customer would come to the website, place items in their shopping cart, and then click the “proceed to checkout button” from the shopping cart. Rather than take them to the cart, our Magento website would immediately forward them to the home page and empty all the items from their cart. Because we could not find a common variable that was causing the issue we couldn’t determine how to fix it. The problem didn’t seem confined to a single browser or platform.
The Solution
With the help of Magento support we determined that the cause of the problem was the ISP providers. It appears that ISPs like AOL, Comcast, and Shaw.ca use a technique of changing IP addresses that cause security settings in Magento to empty the cart and not allow people to check out.
It turns out the fix is fairly simple. Change the Session Validation settings in the Magento Admin, found under System > Configurations > Web, to ‘no’ on everything except “Validate HTTP_USER_AGENT.” After doing this, go to System > Cache Management and refresh the configuration cache to apply the changes.
By applying these fixes to our site, people who could not place orders were suddenly able to do so. When you consider that, perhaps, one person in ten might actually call to complain, I shudder to think of how many sales might have been lost before we applied the fix.
Changing the Session Validation Settings will solve the problem of not allowing certain customers to checkout on your Magento website
See also: Why Johnny Can’t Read Your Web Page…