通过Windows Task Scheduler和HttpClient调用运行的.NET Core 2.1控制台应用程序导致401

Question

I've been running into an issue in upgrading an application from .NET Core 1.0.1 to .NET Core 2.1. This is a console app running via the Windows Task Scheduler that calls a set of web services hosted in IIS on the same server. After the upgrade, when attempting to run it on the host machine, it fails on the first API call, which returns a 401. IIS is set up to accept Anonymous Authentication and Windows Authentication, with the Negotiate and NTLM providers. The task scheduler sets the user that the console app should use. The code that makes the first API call looks like the following:

using (var handler = new HttpClientHandler())
{
   handler.UseDefaultCredentials = true;

   var client = new HttpClient(handler);
   client.DefaultRequestHeaders.Accept.Clear();
   var result = await client.GetStringAsync(myUrlString);
   return Newtonsoft.Json.JsonConvert.DeserializeObject<List<MyResponseObject>>(result);
 }

I've also upgraded the API project to .NET Core 2.1, but I tried reverting back to the 1.0.1 version while running the console app as 2.1 (and conversely, running the API at 2.1 and the console app at 1.0.1 also works) to be sure that it's the console app with the problem.

The console app works fine when running from my localhost with the API hosted locally in IIS Express.

Any help would be much appreciated!

Answer 1

Try this. It work for our client app.

client.DefaultRequestHeaders.Accept.Clear();
client.DefaultRequestHeaders
      .Accept
      .Add(new MediaTypeWithQualityHeaderValue("application/json"));

Answer 2

I've faced similar issue a few weeks ago, when moving from .NET Framework 4.6.x to .NET Core 2.1. The problem may be connected with new HttpHandler implemented in .NET Core 2.1. There are various issues with this handler (for example, this ). Even though this particular bug may not be completely related, the workaround described there may help:

AppContext.SetSwitch("System.Net.Http.UseSocketsHttpHandler", false);