Hmmm... having the same problem, but the solution did nothing -- see "IS THIS THE RIGHT PLACE?" in my code below:
//<*php
foreach( $vars as $name => $value ) {
echo '<input type="hidden" name="'.$name.'" value="'.htmlspecialchars((string)$value).'" />';
}
$doc =& JFactory::getDocument();
$doc->addScriptDeclaration("do_nothing( function() {document.getElementById('hikashop_paypal_form').submit();});");
JRequest::setVar('noform',1);
$vars["address_override"]='0'; // IS THIS THE RIGHT PLACE?
//*>
</form>
</div>
I also tried making sure PayPal address and my HikaShop Customer addresses (both billing and shipping) all matched...
But still get the error.
I do notice that PayPal using only "United States" not "United States of America" -- so I updated that... no change. I still see this error:
Unable to process payment. Please contact the merchant as the shipping address provided by the merchant is invalid, and the merchant has requested that your order must be shipped to that address.