REST API access always returns invalid access when requesting Access Token

Question

I am developing a C# console application that needs to connect to my company's Salesforce sandbox via the API to pull data. After some searching, I am using the nuget package DeveloperForce.Force to help with the connection.

I'm trying to use the OAuth username/password method to get my Access Token without success.

Here is the sample code taken from the Nuget Package project site that I am trying.

class Program
{
    static void Main()
    {
        try
        {
            var task = RunSample();
            task.Wait();
        }
        catch (Exception e)
        {
            Console.WriteLine(e.Message);
            Console.WriteLine(e.StackTrace);
            var innerException = e.InnerException;
            while (innerException != null)
            {
                Console.WriteLine(innerException.Message);
                Console.WriteLine(innerException.StackTrace);
                innerException = innerException.InnerException;
            }
        }
    }

    private static async Task RunSample()
    {
        var auth = new AuthenticationClient();
         // Authenticate with Salesforce
        Console.WriteLine("Authenticating with Salesforce");
        var url = "https://test.salesforce.com/services/oauth2/token";


        await auth.UsernamePasswordAsync("VALID_CLIENT_ID", "VALID_CLIENT_SECRET", "VALID_SALESFORCE_USER", "VALID_SALESFORCE_PASSWORD_AND_SECURITY_TOKEN, url);

        Console.WriteLine("Connected to Salesforce");
        var client = new ForceClient(auth.InstanceUrl, auth.AccessToken, auth.ApiVersion);
        // retrieve all accounts
       Console.WriteLine("Get Accounts");
       const string qry = "SELECT ID, Name FROM Account";
       var accts = new List<Account>();
       var results = await client.QueryAsync<Account>(qry);
       var totalSize = results.totalSize;
       Console.WriteLine("Queried " + totalSize + " records.");
    }
}

Inside the Nuget package code, the request is being made on line 68 with the correct values. However, this request is returning a 400 error saying that the password is invalid. (I have verified all the values are correct and gotten a colleague to confirm this).

In Salesforce I have done the following in hopes to resolve this

• Enabled my Connected App to my custom community
• Created a new Permission Set and linked my Connected App to the user directly

The Connected App has the following scopes (likely overkill, but just trying to get it to work)

• Access and manage your data (api)
• Full access (full)
• Perform requests on your behalf at any time (refresh_token, offline_access)
• Provide access to custom applications (visualforce)
• Provide access to your data via the Web (web)

At this point, I'm thinking there is another setting within Salesforce that I have to set, but I cannot seem to find it. Any help is greatly appreciated.

Answer 1

From the description of the configuration settings on the Connected App, nothing seemed out of place:

1. User was assigned the Connected App through a permission set.
2. Consumer Key and Consumer secret were correct (as confirmed by you and a colleague).
3. Connected App OAuth scopes are correct.
4. User is API Enabled.

My recommended next step after checking these configurations was to try a security token refresh, and that seems to have done the trick. I wish I had a better explanation than sometimes Salesforce seems to be finicky with the security token, but it works often enough for me to be a sort of "Turn it off, and turn it on again"-type solution in my own troubleshooting steps. Perhaps someone else has better insight into the why of this.