Hi @pan999, while I don't know much about using R to generate access tokens, that message from HubSpot's servers means that your grant_type parameter isn't present or are malformed. Taking a look at the httr docs, I'd try to make the request as simple as possible and try work back from there. This section seems to be what you're looking for: https://cran.r-project.org/web/packages/httr/vignettes/quickstart.html#request-body