ASP.NET 5/Core/vNext CORS not working even if allowing pretty much everything

Question

I have a ASP.NET 5 Web API (Well, MVC now anyway) back-end which I am consuming in with the axios library in my JS app.

My CORS config in MVC is the following:

Answer 1

For me helps this:

services.AddCors(options =>{
  options.AddPolicy(AllowAllCorsPolicy, builder =>{
    builder
    .SetIsOriginAllowed(x =>_ = true)
    .AllowAnyMethod()
    .AllowAnyHeader()
    .AllowCredentials();
  });
});

Taken from .