A new X-Cart 5.2.10 is a result of your feedback and X-Cart 5 team prompt reaction to it. 5.2.10 is a non-scheduled release, but devoted to some hot-fixes.
From the point of view of functionality, X-Cart 5.2.9 release was rather extensive, so together with new cool features and improvements it revealed a couple of PHP Fatal errors appearing in certain conditions, and a few other unpleasant bugs. The full list of fixes and updates is available in X-Cart 5 Changelog.
BUG-2410 Call to a member function getCode() on a non-object on the home page if country/state were empty for the default customer address.
BUG-2379 Fixed rate shipping was causing a fatal error on the checkout page.
BUG-2406 Checkout looped after an estimation of the shipping cost was done for a guest customer on the cart page.
BUG-2405 Call to a member function isFreeShipping() on a non-object on the order details page if a coupon used in the order was removed.
We recommend updating your stores now to ensure that the bugs do not cause any trouble to you.