I believe so that you missed when the .NET Core 1.x was upgraded to .NET Core 2.0. For example, if you move ahead and check the existence of
CookieAuthenticationOptions
, you will not find it because it was removed. You need to change your code and then rebuild it. Read my article that I have linked below and check other API changes in the ASP.NET Core 2.0 version below.
ASP.NET Core 2.0 Microsoft.AspNet.Builder API reference[
^]
Read my article covering a few of these points for ASP.NET Core,
Mission Impossible: Migrating .NET Core 1.x to 2.0[
^], lastly never forget to check the API reference for .NET Core at
.NET API Browser | Microsoft Docs[
^]