Access to XMLHttpRequest has been blocked origin ASP.NET CORE 2.2.0 / Angular 8 / signalr1.0.0 [(CORS Policy-Access-Control-Allow-Origin) failed]

来源：https://stackoverflow.com/questions/59468525/access-to-xmlhttprequest-has-been-blocked-origin-asp-net-core-2-2-0-angular-8