Forms9Patch is an enhancement to Xamarin.Forms. As such, first be sure you've met the Xamarin.Forms system requirements.
Forms9Patch requires Xamarin.Forms version 188.8.131.520 or newer.
To use the
background-colorstyle attribute within
Forms9Patch.Label.HtmlTextmarkup text in UWP applications, your UWP applications will need to be built with a minimum Windows version of 10.0.16299.0 (Windows 10 Fall Creators Update).
To build your Android apps, you will need to add the following to your Android application project's