Sandbox issue: "undefined method `authorize' for NilClass:Class"

You may be experiencing the following 500 error when sending requests to our Sandbox environment:

    "error": "UNKNOWN",
    "message": "undefined method `authorize' for NilClass:Class"

To resolve this issue please re-add your test credit card details in your account.

We apologise for the inconvenience, please reach out in comment if you experience further issues regarding this topic.