How to fix “The CORS protocol does not allow specifying a wildcard (any) origin and credentials at the same time” error

Question

I\'ve already enabled CORS on the project in C# .net Core

In startup.cs I\'ve added lines

...
services.AddCors();
...
app.UseCors(builder =         


        

Answer 1

You should have provided the rest of your code... Is this a Blazor client application or Razor Components application (formally known as Server-Side Blazor) ? I guess this is a Blazor client application, right ? Why do you instantiate an HttpClient ? You should use DI (Perhaps Constructor Injection) instead, injecting an HttpClient instance provided by Blazor itself.

The problem is probably server side, though it surfaces as a client one... Try the following:

Get https://www.nuget.org/packages/Microsoft.AspNetCore.Cors/

public void ConfigureServices(IServiceCollection services)
{
    services.AddCors(options =>
    {
        options.AddPolicy("CorsPolicy",
            builder => builder.AllowAnyOrigin()
                .AllowAnyMethod()
                .AllowAnyHeader());
    });
     .....
}

And this:

public void Configure(IApplicationBuilder app, IHostingEnvironment env)    
{
      app.UseCors("CorsPolicy");
}

Note, once again: CORS needs to be enabled on the server side, not in blazor. See https://docs.microsoft.com/en-us/aspnet/core/security/cors for details on how to enable CORS in ASP.NET Core.

Blazor:

 @page "/