type or namespace Task could not be found

问题

I'm using Microsoft Visual Studio express for windows phone, when i use TASK in my app, i get the above mentioned error, even System.Threading.Tasks is also not found. What could be my problem??

回答1:

You need to target at least .NET Framework 4 in your project. You can change this under project properties.

Also, changing the target will not add the reference for the library, so you have to do this manually after changing the target framework.

回答2:

Right click on Task, choose Resolve > System.Threading.Tasks.Task

回答3:

On WP8 (test device Lumia 920), my problem is resolved by following the instructions at: http://www.nuget.org/packages/Microsoft.Bcl.Async

来源：https://stackoverflow.com/questions/19636990/type-or-namespace-task-could-not-be-found