What type of error? Shipping, tax, recalculation etc.
What shipping method(s) is/are enabled?
What tax method is enabled?
What other features are enabled? coupons, gift certificate, customer registration,etc
I haven't seen an issue in my testing. Most of the issues that have been posted to the forum recently about upgrades are caused by the way the host performs the upgrade. Instead of upgrading the store in the place where it is installed, they are moving the store and then upgrading, Moving the store to a new install directory causes urls to change, but the host isn't making the appropriate changes to the stores published pages or their store url settings. That causes add to cart buttons to be broken.