Authentication fails with "access_denied" …why? Naomi June 08, 2018 10:49 Updated Follow This error usually occurs when the user has backed out of the authentication process by using the “back” or “cancel” buttons. Have a look at our comprehensive list of the authentication error descriptions in our API documentation. Related articles API request fails with "wrong_credentials" …why? API request fails with "user_input_required" …why? Comments 0 comments Article is closed for comments.