Handling AD Error When Not Connected

Question

I'm using the below code to get the logge don user's logon name. This works fine when connected to the network/domain. But when offline, I get an error on the 3rd line:

PrincipalServerDownException was unhandled

The server could not be contacted.

Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
    Dim currentADUser As System.DirectoryServices.AccountManagement.UserPrincipal
    currentADUser = System.DirectoryServices.AccountManagement.UserPrincipal.Current
    Dim DisplayName As String = currentADUser.GivenName & " " & currentADUser.Surname
    Label5.Text = DisplayName
    Label4.Text = GetUserProperties()
End Sub

How can I get this to check, and return a userful error to the user, such as "Not on network" or "not connected to domain", then exit? I've tried the below, but this just gives the same error:

Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
    Dim currentADUser As System.DirectoryServices.AccountManagement.UserPrincipal
    If System.DirectoryServices.AccountManagement.UserPrincipal.Current Is Nothing Then
        MsgBox("Network Error: No Connection to Domain")
        Application.Exit()
    Else ....
    End if
End Sub

Answer 1

Use try/catch

    Try
        Dim currentADUser As System.DirectoryServices.AccountManagement.UserPrincipal
        currentADUser = System.DirectoryServices.AccountManagement.UserPrincipal.Current
        Dim DisplayName As String = currentADUser.GivenName & " " & currentADUser.Surname
        Label5.Text = DisplayName
        Label4.Text = GetUserProperties()
    Catch ex As Exception
        MsgBox(...)
    End Try