So, today, while migrating a project to .Net Core, I've encountered a failing unit test that told me this:

Code page 1252 ist the Western European standard code page, but I was obviously missing it. That's where I found svicks post on StackOverflow, which basically explained what went wrong:

In .Net Core, available encodings need to be registered before you can access them.

First, you need to import the System.Text.Encoding.CodePages​ dependency and define a compilation value (I chose NETCORE) in your project.json:

"frameworks": {
    "netcoreapp1.0": {
      "imports": [
        "dnxcore50",
        "portable-net45+win8"
      ],
      "dependencies": {
        "Microsoft.NETCore.App": {
          "version": "1.0.1",
          "type": "platform"
        },
        "System.Text.Encoding.CodePages": "4.0.1"
      },
      "buildOptions": {
        "define": [ "NETCORE" ]
      }
    },
    "net461": {}
  }

Next, register the provider from within your code via conditional compilation:

#if NETCORE
                    Encoding.RegisterProvider(CodePagesEncodingProvider.Instance);
#endif

Happy Encoding=)