Discussion on: Video call with WebRTC Angular and ASP.NET Core

[lan-dry]

Hi. Please I am getting this error:
Access to XMLHttpRequest at 'localhost:5001/signalrtc/negotiate' from origin 'localhost:4200' has been blocked by CORS policy: Response to preflight request doesn't pass access control check: The value of the 'Access-Control-Allow-Origin' header in the response must not be the wildcard '*' when the request's credentials mode is 'include'. The credentials mode of requests initiated by the XMLHttpRequest is controlled by the withCredentials attribute.

can you help me please??

[Sebastian Larrieu]

Hi. As the error show, you have to allow origin localhost:4200 to CORS.

[lan-dry]

But the fact is that I did it exactly as you did. But it stills showing that error. this is the startup file:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.HttpsPolicy;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using signalRtc.hubs;

namespace signalRtc
{
public class Startup
{
readonly string MyAllowSpecificOrigins = "AllowOrigins";

    public void ConfigureServices(IServiceCollection services)
    {
        services.AddCors(options =>
        {
            options.AddPolicy(MyAllowSpecificOrigins,
                builder => builder.WithOrigins("http://localhost:4200", "https://localhost:4200")
                .AllowAnyMethod()
                .AllowAnyHeader()
                .AllowCredentials());
        });

        services.AddSignalR();
    }        

    public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
    {
        if (env.IsDevelopment())
        {
            app.UseDeveloperExceptionPage();
        }

        app.UseRouting();
        app.UseCors(MyAllowSpecificOrigins);
        // app.UseMvc();
        app.UseEndpoints(endpoints =>
        {
            endpoints.MapHub<SignalRtcHub>("/signalrtc");
        });

        app.Run(async(context) =>
        {
            await context.Response.WriteAsync("Hello World!");
        });
    }
}

}

[Sebastian Larrieu]

Hi. As the error shows, you have to allow origin localhost:4200 to CORS. Pleas read the tutorial carefully