An asynchronous operation exceeded the page timeout (trying to use HttpRequestMessage with ASP.NET WebForms page) - asp.net

Question

I have created a web API in AWS that I am trying to get some JSON back from using a web page built in ASP.NET Webforms (most up-to-date version). I can't get the asynchronous part to work. Either the GET method hangs seemingly forever, or - following the best practice approach from the Microsoft documentation - I get this error after a little while:
[TimeoutException: An asynchronous operation exceeded the page
timeout.] System.Web.UI.d__554.MoveNext() +984
I know this is something to do with the wait/async portion of the code and being in ASP.NET because of the following.
If I use very similar code in a console application it works fine.
If i call the web API using POSTMAN it works fine.
I have made async = true in the page directive. Here is my page load
protected void Page_Load(object sender, EventArgs e)
{
try
{
RegisterAsyncTask(new PageAsyncTask(GetStuffAsync));
}
catch (Exception ex)
{
renderStoreCards.Text = ex.Message;
}
}
Here is my method
private async Task GetStuffAsync()
{
string testHtml = string.Empty;
try
{
var signer = new AWS4RequestSigner("AccessKey", "SecretKey");
var request = new HttpRequestMessage
{
Method = HttpMethod.Get,
RequestUri = new Uri("https://some-aws-address-changed-for-stack-overflow.execute-api.ap-southeast-2.amazonaws.com/Prod/tables/InSiteStoreInformation/ServerName")
};
request = await signer.Sign(request, "execute-api", "ap-southeast-2");
var client = new HttpClient();
var response = await client.SendAsync(request).ConfigureAwait(false);
string responseString = await response.Content.ReadAsStringAsync();
}
catch (Exception ex)
{
renderStoreCards.Text = ex.Message;
}
}
The above example produces a TimeoutException. Previous to the above, I was trying the following code. This works fine in a console app, but not in the ASP.NET page.
class Program
{
static void Main(string[] args)
{
try
{
MainAsync().Wait();
}
catch (Exception ex)
{
Console.WriteLine($"Exception occured {ex.Message}");
Console.ReadKey();
}
}
static async Task MainAsync()
{
try
{
var signer = new AWS4RequestSigner("AccessKey", "SecretKey");
var request = new HttpRequestMessage
{
Method = HttpMethod.Get,
RequestUri = new Uri("https://<Hiddenforstackoverflowpost>.execute-api.ap-southeast-2.amazonaws.com/Prod/tables/InSiteStoreInformation/ServerName")
};
request = await signer.Sign(request, "execute-api", "ap-southeast-2");
var client = new HttpClient();
var response = await client.SendAsync(request);
var responseStr = await response.Content.ReadAsStringAsync();
dynamic sales = Newtonsoft.Json.JsonConvert.DeserializeObject(responseStr);
Console.WriteLine($"Server = {sales[0].ServerName}");
Console.ReadKey();
Console.Write(responseStr);
Console.ReadKey();
}
catch (Exception ex)
{
throw (ex);
}
}
}
I am by no means an expert in async/wait combinations, but it appears that the HttpClient I'm using has no synchronous alternative, so I have to figure this out.

Answer 1

I know this is an old question, but I just came across.
The timeouts are most likely caused by ReadAsStringAsync as you neglected to use '.ConfigureAwait(false)' on it. Running async tasks inside ASP.net can be very finicky especially around execution contexts. It most likely is some kind of dead-lock on the async method when it tries to restore the execution context on its return. This usually fails due to the nature of IIS hosting. I am not sure if it actually is a dead-lock or some other issue under the hood. Just make sure to always use .ConfigureAwait(false).
I know this is old, but maybe it helps someone else coming across this issue.