I created a payment gateway for Commerce 2. When I try to make a payment, an error happens and the flash error I get is this "Invalid payment or order. Please review.". I don't know if my gateway is returning the error or Craft. How do I know what is the error especifically?
On the Transactions tab of the order, there should be a payment attempt with a failed status. There's a small information icon which returns the gateway response.