I have my project set to .NET Framework 4.0. When I add System.IO.Packaging, it says that it doesn\'t exist. It also doesn\'t show up when I try to add it as a
System.IO.Packaging
System.IO.Packaging v4.0.30319 is in WindowsBase.dll v4.0.30319
For windows 10 maybe you could found here
C:\Windows\Microsoft.NET\assembly\GAC_MSIL\WindowsBase\v4.0_4.0.0.0__31bf3856ad364e35\