Klarna payment module incopatible with Prestashop

Klarna logoWe got this error after PrestaShop update from 1.4.17 to “Cart can’t be loaded or an order has already been placed using this cart” and we found the solution to this problem.



PrestaShop changed Cart’s class method from:

public function OrderExists()
 $result = Db::getInstance()->ExecuteS('SELECT `id_cart` FROM `'
._DB_PREFIX_.'orders` WHERE `id_cart` = '.(int)($this->id));
 return Db::getInstance()->NumRows();


public function OrderExists()
 return (bool)Db::getInstance()->getValue('SELECT `id_cart` FROM `'
._DB_PREFIX_.'orders` WHERE `id_cart` = '.(int)$this->id);


As you can see now it returns Boolean value not Integer.

Klarna payment module checks if the order exists with current cart with this line:

$cart->OrderExists() === 0

So now this statement returns false instead of true because variable type is not integer. It returned number of rows in earlier versions – so 0 means that there was no any order with the current cart and the statement was correct.

You can find this line in file: modules/kreditor/kreditor.php and in modules/cashondeliverywithfee/cashondeliverywithfee.php.

Check these files and change statement from:

$cart->OrderExists() === 0



It will solve the problem.

It’s early morning now and I hope I described this problem clearly. Well I need more coffee. Hope this post saves somebodies time.

One thought on “Klarna payment module incopatible with Prestashop

  1. Good day,

    I came across your solution while searching the web and it’s exactly the same problem I get when using a Netcash payment module (for South Africa), however I am using PrestaShop Version and I don’t see the folders in the module you are referring to?

    I don’t have kreditor at all and I only have cashondelivery folder but don’t find the code you are referring to.

    Do you have any advice for me? I would really appreciate it.

    Thank you in advance.

    Kind regards,

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