I just got latest stable 184.108.40.206107 and I can't compile anymore
[myUser]\packages\xamarin.forms\220.127.116.11107\build\netstandard1.0\Xamarin.Forms.targets(55,3): error MSB4062: The "Xamarin.Forms.Build.Tasks.GetTasksAbi" task could not be loaded from the assembly [myUser]\.nuget\packages\xamarin.forms\18.104.22.168107\build\netstandard1.0\Xamarin.Forms.Build.Tasks.dll. Confirm that the <UsingTask> declaration is correct, that the assembly and all its dependencies are available, and that the task contains a public class that implements Microsoft.Build.Framework.ITask.
I replaced my user path with [myUser]
it looks like this bug exists since October in the pre-release: