Outh authenticating with curl, but not with C# client

Question

First, I make a curl call using the following format...

curl -v https://login.salesforce.com/services/oauth2/token -d "grant_type=password" -d "client_id=xxx" -d "client_secret=xxx" -d "username=xxx" -d "password=xxx"

This works fine for me. I get back a bearer token no problem.

Second, I make the same call using the C# REST client for Salesforce as described here...

https://github.com/developerforce/Force.com-Toolkit-for-NET/blob/master/src/CommonLibrariesForNET/AuthenticationClient.cs

I plugin the following values...

UsernamePasswordAsync("xxx", "xxx", "xxx", "xxx", "https://login.salesforce.com/services/oauth2/token").Wait();

...but when I plugin these sames variables for the C# REST client for Salesforce I get the error "invalid_grant", "authentication failure"

Any help would be greatly appreciated. FYI - My password format is password/Security token so that shouldn't be the problem?

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Trying this from another angle...

I made the request (succesfully, again) using Postman. Pstman gives you examples for each language you're using so this came up for C#

var client = new RestClient("https://login.salesforce.com/services/oauth2/token");
var request = new RestRequest(Method.POST);
request.AddHeader("postman-token", "xxx");
request.AddHeader("cache-control", "no-cache");
request.AddHeader("content-type", "application/x-www-form-urlencoded");
request.AddParameter("application/x-www-form-urlencoded", "grant_type=password&client_id=xxx&client_secret=xxx&username=xxx&password=xxx", ParameterType.RequestBody);
IRestResponse response = client.Execute(request);

Anyway, tried that and no such luck. Got a "Bad Request" back from http. This totally sucks.

Answer 1

I was able to get this to work by commenting out line 65 in the c# code.

request.Headers.UserAgent.ParseAdd(string.Concat(UserAgent, "/", ApiVersion));

This line sets the UserAgent to the API Version 36.

Edit: I added that line back in and removed the Variables and set them to strings of forcedotcom-toolkit-dotnet and v36.0. This worked for me. Check to ensure you are hitting the correct endpoint (login.salesforce.com for production/dev and test.salesforce.com for sandboxes)