The type name 'ConfigurationSection' could not be found in the namespace 'System.Configuration'. This type has been forwarded to assembly 'System.Configuration.ConfigurationManager, Version=4.0.3.0, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51' Consider adding a reference to that assembly.

Go to NuGet and find: System.Configuration.ConfigurationManager (ran into this trying to port a .NET Framework project to .NET Core) It is the same thing with System.ServiceModel.Primitives (gets around missing ICommunicationObject and CommunicationException in .NET Core) and System.Runtime.Caching