'invalid_request'=>'The request is missing a required parameter, includes an invalid parameter value, includes a parameter more than once, or is otherwise malformed. Check the "%s" parameter.',
'unauthorized_client'=>'The client is not authorized to request an access token using this method.',
'access_denied'=>'The resource owner or authorization server denied the request.',
'unsupported_response_type'=>'The authorization server does not support obtaining an access token using this method.',
'invalid_scope'=>'The requested scope is invalid, unknown, or malformed. Check the "%s" scope.',
'server_error'=>'The authorization server encountered an unexpected condition which prevented it from fulfilling the request.',
'temporarily_unavailable'=>'The authorization server is currently unable to handle the request due to a temporary overloading or maintenance of the server.',
'unsupported_grant_type'=>'The authorization grant type "%s" is not supported by the authorization server',
'invalid_client'=>'Client authentication failed',
'invalid_grant'=>'The provided authorization grant is invalid, expired, revoked, does not match the redirection URI used in the authorization request, or was issued to another client. Check the "%s" parameter.',
'invalid_credentials'=>'The user credentials were incorrect.',
'invalid_refresh'=>'The refresh token is invalid.',