API v1 · OAuth

invalid_client_metadata

HTTP	When
400	The Dynamic Client Registration body is invalid or violates registration policy.

Common causes:

token_endpoint_auth_method other than "none" — v1 supports public clients only.
A grant_types / response_types combination outside authorization_code + refresh_token / code.
Malformed client_name, client_uri, or logo_uri.

The message names the offending field. See OAuth §2.