I have Visual Studio 2012 Express for Web. My Steps -Create a New ASP .NET MVC 4 application -choose basic template -go to Package Manager Console -try to install WebActivat
Change source according to visual studio version
NuGet feed v3 (VS 2015 / NuGet v3.x): https://api.nuget.org/v3/index.json
NuGet feed v2 (VS 2013 and earlier / NuGet 2.x): https://www.nuget.org/api/v2
In my case, I could not install any package and got a similar error. The issue was solved as I unchecked the "Microsoft and .NET" under "Machine-wide package source":
I hope this can be help someone.
I got a similar problem with another package in Visual Studio 2013, I cleared the NuGet package cache with the option "Clear Package Cache" and it works now.
I just ran into this myself. The reference to WebActivatorEx didn't work. You'll have to do it manually. The file is in the packages directory.
So easy
https://www.nuget.org/packages/WebActivator
Need point version of webActivator!!!
PM> Install-Package WebActivator -Version 1.5.3