Type argument Microsoft Runtime CompilerServices ConfiguredTaskAwaitable violates the constraint of type parameter TAwaiter

You add a reference to StackExchange.Redis in your .NET 4.0 project and you get the following exception:

Method System.Runtime.CompilerServices.AsyncTaskMethodBuilder1\[ System.Boolean \].AwaitUnsafeOnCompleted: type argument 'Microsoft.Runtime.CompilerServices.ConfiguredTaskAwaitable1+ConfiguredTaskAwaiter [StackExchange.Redis.ServerEndPoint]’ violates the constraint of type parameter ‘TAwaiter’.

The solution can be found here:

http://blog.marcgravell.com/2014/03/so-i-went-and-wrote-another-redis-client.html?showComment=1405397410965#c8649668071319126908

Try running Update-Package Microsoft.Bcl