Hi Kelly,
Recently I was able to solve the problem and I would like to share the solution that worked for me. My problem was that I have both paypal payments activated 1.- Paypal Standard 2.- Paypal Checkout.
The first step I did was to disable both, then manage the Paypal Checkout with the API account credential and that was it.
Hope this solution works for anyone who gets this error.
I appreciate the answer.
Thanks!
