Question

This class has this description:

Provided for backward compatibility with ASP.NET MVC 3.

And the source is just:

public abstract class AsyncController : Controller
{
}

I can´t find any documentation about deprecation of this class at MSDN. Should I replace uses of AsyncController to Controller?

Answer 1

Should I use AsyncController at ASP.NET MVC 4?

No.

Should I replace uses of AsyncController to Controller?

Yes, asynchronous actions are implemented in new way in asp.net-mvc 4, using Task Class

The ASP.NET MVC 4 Controller class in combination .NET 4.5 enables
you to write asynchronous action methods that return an object of type
Task. The .NET Framework 4 introduced an asynchronous
programming concept referred to as a Task and ASP.NET MVC 4 supports
Task. Tasks are represented by the Task type and related types in the
System.Threading.Tasks namespace. The .NET Framework 4.5 builds on
this asynchronous support with the await and async keywords that make
working with Task objects much less complex than previous asynchronous
approaches. The await keyword is syntactical shorthand for indicating
that a piece of code should asynchronously wait on some other piece of
code. The async keyword represents a hint that you can use to mark
methods as task-based asynchronous methods. The combination of await,
async, and the Task object makes it much easier for you to write
asynchronous code in .NET 4.5. The new model for asynchronous methods
is called the Task-based Asynchronous Pattern (TAP). This tutorial
assumes you have some familiarity with asynchronous programing using
await and async keywords and the Task namespace.

More reading at Using Asynchronous Methods in ASP.NET MVC 4