Sendgrid API: The provided authorization grant is invalid, expired, or revoked

Question

I've just created a sendgrid account. Then I went to settings=>API Keys and clicked on "Create API Key" and gave any possible permission.

Then I've created a c# project, added nuget packages and put my write the hello world code from here

 public async Task HelloEmail()
 {
            dynamic sg = new SendGrid.SendGridAPIClient("XXX-XXXXXXXXXXXXXXXXXX", "https://api.sendgrid.com");

        Email from = new Email("[email protected]");

        String subject = "Hello World from the SendGrid CSharp Library";
        Email to = new Email("[email protected]");
        Content content = new Content("text/plain", "Textual content");
        Mail mail = new Mail(from, subject, to, content);
        Email email = new Email("[email protected]");
        mail.Personalization[0].AddTo(email);

        dynamic response = await sg.client.mail.send.post(requestBody: mail.Get());

        var x=response.StatusCode;
        var y = response.Body.ReadAsStringAsync().Result;
        var z = response.Headers.ToString();
 }

But I get

Unauthorized =>

"{\"errors\":[{\"message\":\"The provided authorization grant is invalid, expired, or revoked\",\"field\":null,\"help\":null}]}"

---

In the example, they got the API key from the EnvironmentVariableTarget.User is it related to that?

string apiKey = Environment.GetEnvironmentVariable("NAME_OF_THE_ENVIRONMENT_VARIABLE_FOR_YOUR_SENDGRID_KEY", EnvironmentVariableTarget.User);
dynamic sg = new SendGridAPIClient(apiKey);

*The problem is that no one reads messages when creating a key, also Microsoft chooses to show us "API Key ID" which is worst name ever

It is not a duplicate because although the reason was the same, no one would guess it since in c# we use a nuget library, not the api.

Answer 1

Something is wrong with your API key. Check this answer, generate a new key, and double check your permissions.

You also don't need to specify the URL in your SendGrid.SendGridAPIClient. I'd remove that line to reduce hardcoded values.