Error on add to cart and remove from mini cart

Hi,

If you look at the response from the server for the AJAX add to cart request with your browser's developers tool you can see this:
i.imgur.com/2OyGT7b.png

This function getCartProductsInfo is defined in the file administrator/components/com_hikashop/classes/cart.php and is used at only one place in HikaShop, in the file components/com_hikashop/controllers/product.php
Both are core files of HikaShop and that this function definitely exists (or the add to cart wouldn't work for anyone using HikaShop since the 4.5.0 has been released) in administrator/components/com_hikashop/classes/cart.php in the latest version of HikaShop (which you have).
So the only conclusion is that either the file administrator/components/com_hikashop/classes/cart.php was modified to remove that function (which I suppose isn't the case, or you would have figured out it came from your modifications), or that you're using an old version of the file administrator/components/com_hikashop/classes/cart.php. This could happen if the joomla installer couldn't replace the file during the update process because of wrong permissions on that file. In that case, you could delete the file and redo an install of the HikaShop install package to add back to correct version of that file.