When I create new ASP.NET 4.5 web forms application from vs2012 and update all nuget packages, I receive this error on build:
I resolved this by following these steps:
1.) Delete Microsoft.Bcl.Build.1.0.13 from solution\packages.
2.) After it Closes the solution, then open the solution.
3.) Navigate to tools/Nuget package manager.
4.) Press Restore Packages in right top corner of the window, after it Re-build the solution.