AspNetCore 3.0 (upgraded from 2.2) routes seem to break when Controller Method has Async suffix

Question

I upgraded my project to Core 3.0 from 2.2 and everything seems to work well, except one get JSON request. I have the following Js code doing an Ajax request to the Home controller:

    var isLastPage = false;
    var incidentModel = {
        incidents: ko.observableArray([]),
        getIncidents: function(a) {
            var self = this;
            //var $incdiv = $('#incidentsList');
            $.getJSON('@Url.Action("AjaxPageAsync", "Home")', { page: page++, user: user, type: type }, function(data) {
                //console.log(data);
                self.incidents(self.incidents().concat(data));
                if (data[0].IsLastPage) {
                    isLastPage = true;
                }
                a();
            });
        }
    }

The Home controller is like this:

public async Task<ActionResult> AjaxPageAsync([FromQuery] string type, [FromQuery] string user, [FromQuery] int? page)
{
       //Get some json data
       return Json(Incident);
}

As you may tell, I'm using knockout (version 3.5.0 & jquery 3.3.0) which both are working fine on other pages. However, the getJSON request in the js code above is returning a 404:

GET https://localhost:44366/Home/AjaxPageAsync?page=1&user=&type=&_=1575386778917 404

The debug output looks similar:

Microsoft.AspNetCore.Hosting.Diagnostics: Information: Request starting HTTP/2.0 GET https://localhost:44366/Home/AjaxPageAsync?page=1&user=&type=&_=1575386536876

The 2.2 version is identical and works fine. I thought it might be the number appended onto the end of the url, but that exists in 2.2 as well.

At this point, I'm thinking it's a problem with the syntax of my AjaxPageAsync task in the controller, but not sure what it should be.

Anyone know where I'm going wrong here? Thank you.

Answer 1

According to https://github.com/aspnet/AspNetCore/issues/8998, in .NET Core 3.0 Async is trimmed from Action name. Your endpoint is available at /Home/AjaxPage. You can change this behaviour by replacing

services.AddControllers();

with

services.AddControllers(options => options.SuppressAsyncSuffixInActionNames = false);

in ConfigureServices method, or just use the new routes