Support Library | Android Developers
Android AppCompat Library V7. ». 28.0.0-alpha3. The Support Library is a static library that you can add to your Android application in order to use APIs that are either not available for older platform versions or utility APIs that aren't a part of the framework APIs. Compatible on devices running API 14 or later.
Android: Failed to resolve: com.android.support:appcompat-v7:28.1.1
Latest version available for Support Libraries is 28.0.0. So, you must update your build.gradle as follows: compile 'com.android.support:appcompat-v7:28..0' Support library was discontinued. So, don't expect any new release after 28.0.0. Google is now supporting AndroidX. In a certain (and basic) way, is the same thing.
Support Library Setup | Android Developers
implementation 'com.android.support:appcompat-v7:28..0' : All com.android.support libraries must use the exact same version specification (mixing versions can lead to runtime crashes). Found versions 28.0.0, 26.1.0. Examples include. com.android.support:animated-vector-drawable:28... and . com.android.support:support-v4:26.1.
Migrating to AndroidX: tips, tricks, and guidance - Medium
dotnet add package Xamarin.Android.Support.v7.AppCompat --version 28.0.0.3. README. Frameworks. Dependencies. Used By. Versions. Xamarin.Android bindings for Android Support Library - appcompat-v7.