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Task.ContinueWith Method (Action<Task>, CancellationToken, TaskContinuationOptions, TaskScheduler)

Creates a continuation that executes according to the specified TaskContinuationOptions.

Namespace:  System.Threading.Tasks
Assembly:  mscorlib (in mscorlib.dll)

public Task ContinueWith(
	Action<Task> continuationAction,
	CancellationToken cancellationToken,
	TaskContinuationOptions continuationOptions,
	TaskScheduler scheduler


Type: System.Action<Task>
An action to run according to the specified continuationOptions. When run, the delegate will be passed the completed task as an argument.
Type: System.Threading.CancellationToken
The CancellationToken() that will be assigned to the new continuation task.
Type: System.Threading.Tasks.TaskContinuationOptions
Options for when the continuation is scheduled and how it behaves. This includes criteria, such as OnlyOnCanceled, as well as execution options, such as ExecuteSynchronously.
Type: System.Threading.Tasks.TaskScheduler
The TaskScheduler to associate with the continuation task and to use for its execution.

Return Value

Type: System.Threading.Tasks.Task
A new continuation Task.


The Task has been disposed.


The CancellationTokenSource that created the token has already been disposed.


The continuationAction argument is null.


The scheduler argument is null.


The continuationOptions argument specifies an invalid value for TaskContinuationOptions.

The returned Task will not be scheduled for execution until the current task has completed. If the criteria specified through the continuationOptions parameter are not met, the continuation task will be canceled instead of scheduled.

The following is an example of using ContinueWith to run work both in the background and on the user interface threads.

// C#

private void Button1_Click(object sender, EventArgs e)


var backgroundScheduler = TaskScheduler.Default;

var uiScheduler = TaskScheduler.FromCurrentSynchronizationContext();

Task.Factory.StartNew(delegate { DoBackgroundComputation(); }, backgroundScheduler).

ContinueWith(delegate { UpdateUI(); }, uiScheduler).

ContinueWith(delegate { DoAnotherBackgroundComputation(); }, backgroundScheduler).

ContinueWith(delegate { UpdateUIAgain(); }, uiScheduler);


' Visual Basic

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click

Dim backgroundScheduler = TaskScheduler.Default

Dim uiScheduler = TaskScheduler.FromCurrentSynchronizationContext()



End Sub, backgroundScheduler).ContinueWith(Sub(t)


End Sub, uiScheduler).ContinueWith(Sub(t)


End Sub, backgroundScheduler).ContinueWith(Sub(t)


End Sub, uiScheduler)

End Sub

.NET Framework

Supported in: 4

.NET Framework Client Profile

Supported in: 4

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.