I am trying to build a sample application using EF7 and mvc 6 in visual studio 2015 pre release.
While installing both EF7 and MVC6 using package manager console getting
I have solved this problem, by disabling the "https://api.nuget.org/v3/" from the package source, in order to do this, Choose Tools > Nuget Package Manager > Package Source
And other thing I did is added myget package source "https://www.myget.org/F/aspnetvnext/api/v2/"
Following the steps Choose Tools > Nuget Package Manager > Package Source > Click add on top of the window and add the myget package source.