This affects modules up to version 17.4.1 for Magento 1. The problem is resolved in later versions.
When trying to make a payment using a saved credit card (Alias payment method), the payment fails.
However, making direct payments with a credit card (not using a stored one) works fine.
This problem can occur with module versions up to 17.4.1 in conjunction with PHP 5.x.
The root cause is the incorrectly transmitted parameter HTTP_ACCEPT.
This problem is resolved in newer versions (after 17.4.1).
Alternatively, you can apply the patch that is attached to this article.