Dropbox .net SDK, automatic refresh of access token not working

I've managed to sort the issue. Debugging through the SDK source code, I could see that I wasn't setting the AppSecret, though from the comments in the SDK, it appears that this is not critical. However when I changed the code I use to create the Dropbox client and used the overload that includes the AppSecret, the SDK was able to retrieve a refresh token.

It would be useful if the proper error messages received from the server is returned from the API call. For example when the RefreshAccessToken method is called in the DropboxRequestHandler, the call to response.EnsureSuccessStatusCode() (on line 288) throws an exception which causes the method to only return the basic information, in this case BadRequest provided by that exception. Instead, what you really should be doing is creating some custom code to handle a non Success status code then if possible, you need to be parsing the Content of the response like you do for a successful request i.e.  var json = JObject.Parse(await response.Content.ReadAsStringAsync()) which will then provide you with additional error information that you can pass on to the user which will at least give them a clue, in my case it was the "No auth function available for given request" message which provided a bit of a clue.

For example, something a bit like this.....

string Error = null;

try
{
response.EnsureSuccessStatusCode();
}
catch (Exception ex)
{
Error = ex.Message
}

var json = JObject.Parse(await response.Content.ReadAsStringAsync());

if (!string.IsNullOrEmpty(Error)
{
// Do something with the decoded json data and then maybe throw a new exception with this data
}


            if (response.IsSuccessStatusCode)
            {
                var json = JObject.Parse(await response.Content.ReadAsStringAsync());
                string accessToken = json["access_token"].ToString();
                DateTime tokenExpiration = DateTime.Now.AddSeconds(json["expires_in"].ToObject<int>());
                this.options.OAuth2AccessToken = accessToken;
                this.options.OAuth2AccessTokenExpiresAt = tokenExpiration;
                return true;
            }

            return false;

Also, since in this case it was the lack of AppSecret that was causing the issue, an error reflecting this would be very useful.