FromBluetoothAddressAsync IAsyncOperation does not contain a definition for 'GetAwaiter' error

To await an IAsyncOperation, you need two things:

• A reference to C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\.NETCore\v4.5\System.Runtime.WindowsRuntime.dll
• A reference to C:\Program Files (x86)\Windows Kits\10\UnionMetadata\Facade\Windows.WinMD

If either reference is missing then it won't work. You can also use the UwpDesktop nuget package, that will do the work for you.

Note: specifically GetAwaiter is extension in System namespace that is available from those references (you still need using System; - make sure you have not removed it from the file). The extension info is on MSDN - WindowsRuntimeSystemExtensions.GetAwaiter.

For some of the other UWP operations just add using System:

using System;

//...

// example - getting file reference:
var file = await Windows.Storage.ApplicationData.Current.LocalFolder.GetFileAsync("myFile.txt);