Xamarin cross-platform (portable class) project compilation error

Question

I made a new blank cross-platform project using a portable class library in visual studio, BUT when I try to build a platform project I have a list of errors:

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Answer 1

I have created a new Xamarin.forms project (blank shared) with VS2015 Update 3 RC and similar problems (and more, e.g. 'Resource.Attribute' does not contain a definition for 'actionBarSize'.
The problem was the sub-version of JDK (Update 55 instead of Update 79).
You can find my posting to the Resource.Attribute error here: JDK7 problem

Answer 2

You need to use the specific/minimium versions of the packages that are mentioned in the error message. The safest way to do it is to remove all nuget packages (including Xamarin.Forms) and then add Xamarin.Forms nuget package, which will add all its dependencies with the specific versions.

Explanation, by James Montemagno:

Xamarin.Forms locks in a very specific version of the support libraries and google play services. You can't update them because Xamarin.Forms isn't compatible with them as it would need to be re-compiled.

Xamarin.Android.Support.v4 (= 23.0.1.3)

Xamarin.Android.Support.Design (= 23.0.1.3)

Xamarin.Android.Support.v7.AppCompat (= 23.0.1.3)

Xamarin.Android.Support.v7.CardView (= 23.0.1.3)

Xamarin.Android.Support.v7.MediaRouter (= 23.0.1.3)

See the = 23.0.1.3, which means it is only compatible with that version number. This is just how NuGet works. When Xamarin.Forms updates these packages will auto update.