I had created an app and when tried to run,get an error like this.
ERROR: In MenuView, unable to find attribute android:preserveIco
I think switched the API Level is not a genuine solution. We can resolve this by follows these steps:
Go to "C:\Users\AjaySharma\AppData\Local\Xamarin\Android.Support.v7.AppCompat\20.0.0\content\support\v7\appcompat\res\values\attrs.xml"
(Pleae make sure , change USer name and Target version in path)
Find "android:preserveIconSpacing" in file and remove or comment this entire line.
Now, You can Build Seccessfully. For more details. Read this