Last page after checking out shows error

-- HikaShop version -- : 2.6.1
-- Joomla version -- : 3.4.8
-- PHP version -- : 5.4.45
-- Browser(s) name and version -- : sarfari 9.0
-- Error-message(debug-mod must be tuned on) -- : 500 JHtmlBehavior::mootools not found

I have a few pages where checkout happens (one for products, one for vendors, one for sponsors) the result of selecting products, and checking out with the cart works. But when the Finish button is pressed and the transaction is processed, I end up on an error page (not even my stylized error page) and the error message is: 500 JHtmlBehavior::mootools not found.

I've searched the forum and haven't found the answer. Please help. How do I get my folks to a simple "thank you for your order" page that is an article?

Got it. Errors are gone. Now it goes to a tiny, "Thank you for your purchase." How do I get that to redirect to send clients to a specific article?

Hi,

You can set the url of the desired article in the option "Return url" of your payment method.

Return url : The url you want your users to be redirected to when they finish their payment on the paypal interface. By default, they will be redirected to the after_end page of the checkout process which will thank them for their order.