Do not use— is not supported by PackWebRequest.
Assembly: PresentationCore (in PresentationCore.dll)
Occurs on any call to . The pack URI protocol does not support writing.
Windows 7, Windows Vista SP1 or later, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later)
The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.