title: Errors when changing Android version (Target Framework) in Xamarin Forms
body: <p>I have a C# Xamarin Forms Solution in Visual Studio 2019 that was created from the  Xamarin Forms Template.</p>
  
  <p>When the Android version (Target Framework), (found in the 'Application' Tab of the properties Window of the Android project) is set to either</p>
  
  <p>1) Android 8.1 (Oreo)</p>
  
  <p>2) Android 9.0 (Pie)</p>
  
  <p>then my app works great on a phone running Android 9.0</p>
  
  <p>However, as soon as I change it to 'Android 8.0 (Oreo)' then Visual Studio generates errors and warnings. Here is an image of them:</p>
  
  <p><a href="https://i.stack.imgur.com/vLVXT.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/vLVXT.png" alt="Errors"></a></p>
  
  <p>The reason I think I need to change the Android version to 8.0 is so that I can use the app on Android phones with this version. When I try to install the APK file (built targeting either 8.1 or 9.0) on an 8.0 Android device then the app does not work.</p>
  
  <p>The error suggestion to "..increase the $(TargetFrameworkVersion)..." seems odd considering I am trying to target a lower version. </p>
  
  <p>I should point out that I have all the Android SDK's installed for 8.0/8.1/9.0 and all the Android SDK Build Tools.</p>
  
  <p>What am I doing wrong? I am wanting to target Android 8.0 (Oreo).</p>
  
  <p>I am very new to Xamarin.</p>