Payflow Pro error: "Payment error #1 User authentication failed"

Usually this error appears when there is something wrong the your saved API credentials in the gateway settings. Those are Partner, Merchant login, User and Password.

To fix that we recommend you to remove the existing credentials that you have in your settings to clear the fields and hit "Save changes". Then re-enter the credentials back into the fields carefully and hit "Save changes" again.

Now you can check if the problem is gone or not.