Magento 2 : Error "Unable to create credit memo for order"

Question

I am getting this error while online refunding credit memo using a script.

"Unable to create credit memo for order" error appear, this is due to this https://github.com/pepe1518/magento2/blob/89adbabc2a295c9b6f88768d541fd2858f59aae5/vendor/magento/module-sales/Model/Order.php#L603

I want to know in which conditions, this error come ?

Answer 1

You need to debug code step by step, add logs in your main logic after line by line. Check from where the logic fails. This error is caused when there is no item passed to refund array (ordered item id) should be passed in order to process refund.

Answer 2

See this for how flag ForcedCanCreditmemo property was set. Note that this property is just for current instance not a field in database, also cannot be saved.

https://github.com/magento/magento2/blob/2.4-develop/app/code/Magento/Payment/Observer/SalesOrderBeforeSaveObserver.php

It seem like Creditmemo for free transactions is not possible.

But if you might want to customize it, add this flag on observer event sales_order_load_after

if($order->getPayment()->getMethodInstance()->getCode() === 'free') {
    $order->setForcedCanCreditmemo(true);
}