When your computer says no, it's helpful to know how to make it say yes. Below is a summary of error codes and corresponding HTTP status codes for the OAuth 2.0 flow.
|invalid_request 400||The request is malformed, a parameter has an invalid value or is missing.|
|invalid_client 401||Client authentication failed.|
|unauthorized_client 400||Client is not authorised to use the grant.|
|unsupported_grant_type 400||Authorisation grant is not supported by the Authorisation Server.|
|invalid_scope 400||The scope is malformed or invalid.|