Authlete APIs return result codes starting with "A".
http://docs.authlete.com/#result-codes

The third digit from the right has a meaning as is listed below:

0: Success
1: Error in Authlete.
2: Error in Service.
3: Error in Client.
4: Just logging.
5: Error in Authlete Front-End.
6: Error in user operation (Service Owner, Developer, End-User).
7: Error in external SNS.

Please refer this when building your authorization server(s) with Authlete.