IApplicationBuilder dos not contain a definition UseEndpoints. app.UseEndpoints(...) not workin on ASP.NET CORE

I'm trying to incorporate signalR on my project, but when I try to use app.UseEndpoints(...) it gives me an error saying that "IApplicationBuilder does not contain UserEndpoints. Here is the code on my StartUp class:

    // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
    public void Configure(IApplicationBuilder app, IHostingEnvironment env)
    {


        if (env.IsDevelopment())
        {
            app.UseDeveloperExceptionPage();
            app.UseDatabaseErrorPage();
        }
        else
        {
            app.UseExceptionHandler("/Home/Error");
            app.UseHsts();
        }


        app.UseHttpsRedirection();
        app.UseStaticFiles();
        app.UseCookiePolicy();

        app.UseAuthentication();

        //SIGNAL R - ERROR
        app.UseEndpoints(endpoints =>
        {
            endpoints.MapHub<ChatHub>("/myHub");
        });



        app.UseMvc(routes =>
        {
            routes.MapRoute(
                name: "default",
                template: "{controller=Home}/{action=Index}/{id?}");
        });
    }
}

What should I do?

My Hub:

 public class MyHub : Microsoft.AspNet.SignalR.Hub
   {
    public async Task PostMarker(string latitude, string longitude) 
    {
        await Clients.All.SendAsync("ReceiveLocation", latitude, longitude);
    }
}

As per your comment, you are targeting .NET Core 2.1, but the UseEndpoints extension method was introduced in 3.0.

To add SignalR in 2.1, firstly make sure you have services.AddSignalR(); in your ConfigureServices method. Secondly, you should use app.UseSignalR in the Configure method, instead of UseEndpoints.

Like so:

app.UseSignalR(route =>
{
    route.MapHub<MyHub>("/myHub");
});