不使用异步功能时出现异步错误？

Question

I have this function as part of a api to update data after a payment has been confirmed. It all works and updates the data but fails to redirect to the specified URl and throws this error:

I don't understand why I'm getting it as I'm not using async anywhere? Help would be appreciated.

public HttpResponseMessage PaymentConfirmed(string id, string email, string status, string amount, string product)
{
    if(status == "Paid")
    {
        var Id = id;
        var Email = email;

        var uid = Convert.ToInt32(Id);
        var userbyId = RepositoryHelper.GetPersonFromId(uid);
        if (userbyId.UserType == "Donation")
        {
            RepositoryHelper.UpdateDonation(userbyId, amount);
        }
        if (userbyId.UserType == "Sponsor")
        {
            var school = RepositoryHelper.GetSchoolByUser(userbyId);
            RepositoryHelper.AddFreeUsers(school);
        }
        if (userbyId.UserType == "School" || userbyId.UserType == "Pupil")
        {
            var complete = RepositoryHelper.UpgradeToPaid(userbyId);
        }

        SendUserPaymentConfirmed(userbyId);

        HttpResponseMessage response = Request.CreateResponse(HttpStatusCode.Moved);
        response.Headers.Location = new Uri("http://url here");
        return response;
    }
    return null;
}

Answer 1

You can try by putting an await in front of these method calls like:

await RepositoryHelper.UpdateDonation 
await RepositoryHelper.AddFreeUsers
await RepositoryHelper.UpgradeToPaid
await SendUserPaymentConfirmed

Then in method declaration change it :

public Task<HttpResponseMessage> PaymentConfirmed

Build the project and fix where there are errors. Most likely the methods that does not support async will complain or will have errors. Then run the API again and see if you still get the same error.

Answer 2

user error!!!!!!

Found the issue, although my send message returned a void it had this nestled within it client.SendAsync(mailMessage, null);

Removed it and all works fine