I did the upgrade when I saw the notification in my WP Dashboard.
Now when clicking Place Order I get an error saying "sorry this page does not exist"
I've had a bit of a play around and I thought the upgrade had trashed some pages, but it still doesn't work.
I'm using the Sagepay Form Gateway plug-in By PatSaTECH and it's worked pefectly until this update.
It's basically stopped the step between clicking the button and handing over to Sagepay.