Amazon Cognito and ASP.NET C# Integration

Question

Hello, I am trying to implement cognito user pool into my login, register and logout and I have tried this code for Signup

protected void Button1_Click(object sender, EventArgs e)
{
   AddCognitoUser();
}
static async Task AddCognitoUser()
{
   string username = "Name";
   string password = "Password";
   string phonenumber = "[phone]";
   string email = "[email protected]";
   AmazonCognitoIdentityProviderClient provider =
      new AmazonCognitoIdentityProviderClient(new Amazon.Runtime.AnonymousAWSCredentials());
   SignUpRequest signUpRequest = new SignUpRequest();
   signUpRequest.ClientId = "clientid";
   signUpRequest.Username = username;
   signUpRequest.Password = password;

   AttributeType attributeType = new AttributeType();
   attributeType.Name = "phone_number";
   attributeType.Value = phonenumber;
   signUpRequest.UserAttributes.Add(attributeType);

   AttributeType attributeType1 = new AttributeType();
   attributeType1.Name = "email";
   attributeType1.Value = email;
   signUpRequest.UserAttributes.Add(attributeType1);

   try
   {
      SignUpResponse result = await provider.SignUpAsync(signUpRequest);
   }
   catch (Exception e)
   {
      System.Diagnostics.Debug.WriteLine(e);
   }
}

When i run these codes, there is an error saying "An unhandled exception of type 'System.NullReferenceException' occurred in mscorlib.dll" and i tried to find but there is nothing null in the codes. Is there anything that i do wrong?

 

Or is there any other better tutorial that help to integrate cognito with asp.net c#?

 

Any help will be really helpful.

Thank You.