Power BI message- M Language - Failure to Request a json service API -

HI JoseJunior22,

I think this may be related to your API authorization, the 'anonymous' mode is set on the root URL instead of the detailed API URL. Perhaps you can add the relative path option to handle this scenario:

let
    body = "{'grant_type' : 'client_credentials'}",
    rootURL = "https://api-sandbox.anbima.com.br",
    _tokenPath = "/oauth/access-token",
    getToken =
        Json.Document(
            Web.Contents(
                rootURL,
                [
                    Headers = [
                        #"Content-Type" = "application/json",
                        #"Authorization" =
                            "Basic "
                            & Binary.ToText(
                                Text.ToBinary("Uw6QvcZwzRtp:qaRCeKStnXhE"),
                                0
                            )
                    ],
                    RelativePath = _tokenPath,
                    Content = Text.ToBinary(body)
                ]
            )
        ),
    access_token = getToken[access_token],
    authToken = "bearer " & access_token,
    //urlRequest= path & "/feed/precos-indices/v1/titulos-publicos/curvas-juros",
    _relativePath = "/feed/precos-indices/v1/titulos-publicos/mercado-secundario-TPF",
    //keyPhrases = KeyPhrases(),
    results =
        Json.Document(
            Web.Contents(
                rootURL,
                [
                    Headers = [
                        #"Content-Type" = "application/json",
                        client_id = "Uw6QvcZwzRtp",
                        access_token = authToken
                    ],
                    RelativePath = _relativePath
                // Headers=[Accept="application/json",#"Authorization"=authToken]
                // Headers = [#"Authorization"=authToken]
                ]
            )
        )
in
    results

Chris Webb's BI Blog: Using The RelativePath And Query Options With Web.Contents() In Power Query And Power BI M Code Chris Webb's BI Blog (crossjoin.co.uk)

Regards,

Xiaoxin Sheng