Web Api请求引发“将内容复制到流时出错".

我正在尝试实现此代码示例，但得到 HttpRequestException -"将内容复制到流中时发生错误."调用 ReadAsStringAsync()方法时.内部的例外是"无法访问已处置的对象".我正在使用Fiddler发出请求.我不明白有人可以解释为什么我遇到此异常并提供解决方案吗?

I'm trying to implement this code example, but get a HttpRequestException - "Error while copying content to a stream." when the ReadAsStringAsync() method is called. The inner exception is "Cannot access a disposed object." I'm using Fiddler to make the request. I don't understand. Can someone explain why I'm getting this exception and offer a solution?

Web Api方法:

Web Api Method:

public async Task<HttpResponseMessage> Post(HttpRequestMessage request)
{
    try
    {
        var jsonString = await request.Content.ReadAsStringAsync();
    }
    catch (Exception ex)
    {                
        throw;
    }
    return new HttpResponseMessage(HttpStatusCode.Created);
}

提琴手(POST):

User-Agent: Fiddler
Host: localhost:23567
Content-Length: 18
Content-Type: application/json; charset=utf-8
Body{"Test":1}

我有一个线索，但需要验证.在Web Api控制器上，我有一个 ActionFilterAttribute ，在其 OnActionExecuting 覆盖中，有以下一行:

I have a clue, but need verification. On the Web Api controller, I have an ActionFilterAttribute and in its OnActionExecuting override, there's this line:

public override async void OnActionExecuting(HttpActionContext actionContext)
{
    // omitted code
    actionContext.Request.Content.ReadAsStreamAsync();
}

可能是因为这里读取了内容，所以不再可用了吗?如果是这样，如何在方法中使用它?这里的内容与HttpRequestMessage相同吗?这可能包含一个答案.

Could it be that because the Content is read here, it's not available again? If so, how can I make it available in the method? Is the Content here the same as the HttpRequestMessage? This may contain an answer.