Xamarin.Forms.2.3.4.247 update : project won't build

Hi,

I just updated Xamarin.Forms to version 2.3.4.247 as well as a couple of other packages, and I get this error, completely new for me:

...\portable-win+net45+wp80+win81+wpa81+MonoAndroid10+Xamarin.iOS10+xamarinmac20\Xamarin.Forms.targets(68,4): error MSB4064: The "DebugType" parameter is not supported by the "XamlCTask" task. Verify the parameter exists on the task, and it is a settable public instance property.
...\portable-win+net45+wp80+win81+wpa81+MonoAndroid10+Xamarin.iOS10+xamarinmac20\Xamarin.Forms.targets(62,3): error MSB4063: The "XamlCTask" task could not be initialized with its input parameters.

Any idea of possible cause of this error?

The project was initially working with Xamarin.Forms 2.3.1.114, it is a PCL project, not using XMAL.

Thank you.