ApplicationDeployment.CheckForUpdate Method

Definition

Namespace:

System.Deployment.Application

Assembly:

System.Deployment.dll

Checks UpdateLocation to determine whether a new update is available.

Overloads

CheckForUpdate()	Checks UpdateLocation to determine whether a new update is available.
CheckForUpdate(Boolean)	Checks UpdateLocation to determine whether a new update is available.

CheckForUpdate()

Checks UpdateLocation to determine whether a new update is available.

public:
 bool CheckForUpdate();

public bool CheckForUpdate ();

member this.CheckForUpdate : unit -> bool

Public Function CheckForUpdate () As Boolean

Returns

Boolean

true if a new update is available; otherwise, false.

Exceptions

InvalidOperationException

ClickOnce throws this exception immediately if you call the CheckForUpdate() method while an update is already in progress.

DeploymentDownloadException

The deployment manifest cannot be downloaded.

InvalidDeploymentException

The deployment manifest is corrupted. You will likely need to redeploy the application to fix this problem.

Examples

The following code example checks for an application update; if one is available, it installs it synchronously.

public:
    void LaunchUpdateWithTimeout()
    {
        if (ApplicationDeployment::IsNetworkDeployed)
        {
            ApplicationDeployment^ appDeployment =
                ApplicationDeployment::CurrentDeployment;
            appDeployment->UpdateCompleted +=
                gcnew AsyncCompletedEventHandler(this, 
                &Form1::deploy_UpdateCompleted);

            // The Interval property uses millisecond resolution.
            timer1->Interval = (1000 * 60) * 2;
            timer1->Start();

            appDeployment->UpdateAsync();
        }
    }

private:
    void deploy_UpdateCompleted(Object^ sender,
        AsyncCompletedEventArgs^ e)
    {
        timer1->Stop();
        if (!e->Cancelled)
        {
            if (nullptr == e->Error)
            {
                Application::Restart();
            }
            else
            {
                // Replace with your own error reporting or logging.
                MessageBox::Show(
                    "The update of the application encountered an " +
                    "error. Error message: {0}",
                    e->Error->Message);
            }
        }
        else
        {
            // Replace with your own error reporting or logging.
            MessageBox::Show(
                "The application update was cancelled because the update " +
                "server was unreachable. Please try again later.");
        }
    }

private:
    void timer1_Tick(Object^ sender, EventArgs^ e)
    {
        if (ApplicationDeployment::IsNetworkDeployed)
        {
            ApplicationDeployment::CurrentDeployment->UpdateAsyncCancel();
        }
    }

private void InstallUpdateSync()
{
    if (ApplicationDeployment.IsNetworkDeployed)
    {
        Boolean updateAvailable = false;
        ApplicationDeployment ad = ApplicationDeployment.CurrentDeployment;

        try
        {
            updateAvailable = ad.CheckForUpdate();
        }
        catch (DeploymentDownloadException dde)
        {
            // This exception occurs if a network error or disk error occurs
            // when downloading the deployment.
            MessageBox.Show("The application cannt check for the existence of a new version at this time. \n\nPlease check your network connection, or try again later. Error: " + dde);
            return;
        }
        catch (InvalidDeploymentException ide)
        {
            MessageBox.Show("The application cannot check for an update. The ClickOnce deployment is corrupt. Please redeploy the application and try again. Error: " + ide.Message);
            return;
        }
        catch (InvalidOperationException ioe)
        {
            MessageBox.Show("This application cannot check for an update. This most often happens if the application is already in the process of updating. Error: " + ioe.Message);
            return;
        }

        if (updateAvailable)
        {
            try
            {
                ad.Update();
                MessageBox.Show("The application has been upgraded, and will now restart.");
                Application.Restart();
            }
            catch (DeploymentDownloadException dde)
            {
                MessageBox.Show("Cannot install the latest version of the application. Either the deployment server is unavailable, or your network connection is down. \n\nPlease check your network connection, or try again later. Error: " + dde.Message);
            }
            catch (TrustNotGrantedException tnge)
            {
                MessageBox.Show("The application cannot be updated. The system did not grant the application the appropriate level of trust. Please contact your system administrator or help desk for further troubleshooting. Error: " + tnge.Message);
            }
        }
    }
}

Private Sub InstallUpdateSync()
    If (ApplicationDeployment.IsNetworkDeployed) Then
        Dim updateAvailable As Boolean = False
        Dim AD As ApplicationDeployment = ApplicationDeployment.CurrentDeployment

        Try
            updateAvailable = AD.CheckForUpdate()
        Catch dde As DeploymentDownloadException
            ' This exception occurs if a network error or disk error occurs
            ' when downloading the deployment.
            MessageBox.Show("The application cannot check for the existence of a new version at this time. " & ControlChars.Lf & ControlChars.Lf & "Please check your network connection, or try again later. Message: " & dde.Message)
            Exit Sub
        Catch ide As InvalidDeploymentException
            MessageBox.Show("The application cannot check for an update. The ClickOnce deployment is corrupt. Please redeploy the application and try again. Message: " & ide.Message)
            Exit Sub
        Catch ioe As InvalidOperationException
            MessageBox.Show("The application cannot check for an update. This most likely happened because the application is already updating. Message: " & ioe.Message)
            Exit Sub
        End Try

        If (updateAvailable) Then
            Try
                AD.Update()
                MessageBox.Show("The application has been upgraded, and will now restart.")
                Application.Restart()
            Catch dde As DeploymentDownloadException
                MessageBox.Show("Cannot install the latest version of the application. " + ControlChars.Lf + ControlChars.Lf + "Please check your network connection, or try again later.")
            End Try
        End If
    End If
End Sub

Remarks

The CheckForUpdate method compares the version of the currently installed deployment with the version specified in the deployment manifest found at UpdateLocation. If the version on the server is different from the installed version, it returns true.

This method will block until the check has completed. To check for an update asynchronously, use the CheckForUpdateAsync method instead.

Note

If CheckForUpdate discovers that an update is available, and the user chooses not to install it, ClickOnce will prompt the user that an update is available the next time the application is run. There is no way to disable this prompting. (If the application is a required update, ClickOnce will install it without prompting.)

See also

• CheckForUpdateAsync()
• CheckForDetailedUpdate()

CheckForUpdate(Boolean)

Checks UpdateLocation to determine whether a new update is available.

public:
 bool CheckForUpdate(bool persistUpdateCheckResult);

public bool CheckForUpdate (bool persistUpdateCheckResult);

member this.CheckForUpdate : bool -> bool

Public Function CheckForUpdate (persistUpdateCheckResult As Boolean) As Boolean

Parameters

persistUpdateCheckResult

Boolean

If false, the update will be applied silently and no dialog box will be displayed.

Returns

Boolean

true if a new update is available; otherwise, false.