c# - ASHX 处理程序中的异步发布

Question

我在使用 ASHX 处理程序时遇到问题。下面这段代码在本地机器上工作正常，但在服务器上不工作。

public void ProcessRequest(HttpContext context)
{
    ...... More code
    // convert class to namevaluecollection
    NameValueCollection formFields = payloadData.ToNameValueCollection();

    using (var client = new WebClient())
    {
        //client.Headers["Content-Type"] = "application/x-www-form-urlencoded";
        client.UploadValuesAsync(new Uri("http://server/accept"), "POST", formFields);
    }
}

我收到以下错误:

Exception type: InvalidOperationException 
    Exception message: An asynchronous operation cannot be started at this time. 
    Asynchronous operations may only be started within an asynchronous handler or module or during certain events in the Page lifecycle.
    If this exception occurred while executing a Page, ensure that the Page is marked <%@ Page Async="true" %>.
    This exception may also indicate an attempt to call an "async void" method, which is generally unsupported within ASP.NET request processing.
    Instead, the asynchronous method should return a Task, and the caller should await it.

编辑:

我发现的一件事可能是版本对代码库的影响。有人可以确认 UploadValuesAsync 在框架 4.5 和 4.6 上的行为不同

Answer 1

这将异步发布:

Task.Run(() => PostAsync());