System.NullReferenceException when trying to read registry key VisualBasic

Question

I'm trying to make the checkbox filled when Launcher_SessionLoginAnimation_OnShow is set to 1. I can't seem to fix a problem which is causing a System.NullReferenceException. I tried searching google and stackexchange, but I couldn't find a solution.

Imports Microsoft.Win32
Public Class Form1
    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        Dim subKeyName As String = "SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\ImmersiveShell\\Grid"
        Dim key As RegistryKey = Microsoft.Win32.Registry.LocalMachine.OpenSubKey(subKeyName)
        If key IsNot DBNull.Value Then
            Dim readValue As String = key.GetValue("Launcher_SessionLoginAnimation_OnShow")
            If readValue.Equals("1") Then
                CheckBox1.Checked = True
            End If
        End If
    End Sub

    Private Sub CheckBox1_CheckedChanged(sender As Object, e As EventArgs) Handles CheckBox1.CheckedChanged
        If CheckBox1.Checked = True Then
            Dim key = Microsoft.Win32.Registry.CurrentUser.OpenSubKey(
                  "SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\ImmersiveShell\\Grid", True)
            If key IsNot Nothing Then
                key.SetValue("Launcher_SessionLoginAnimation_OnShow", 1)
                key.Close()
            End If
        Else
            Dim key = Microsoft.Win32.Registry.CurrentUser.OpenSubKey(
                  "SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\ImmersiveShell\\Grid", True)
            If key IsNot Nothing Then
                key.SetValue("Launcher_SessionLoginAnimation_OnShow", 0)
                key.Close()
            End If
        End If
    End Sub
End Class

Where readValue As String = key.GetValue("Launcher_SessionLoginAnimation_OnShow") throws System.NullReferenceException Can anyone help me fix this problem? Any help is appreciated.

From MSDN: `Returns: The value associated with name, or Nothing if name is not found.` You should also turn on `Option Strict`. For more on a NullReferenceException, see [NullReference Exception in Visual Basic](http://stackoverflow.com/a/26761773/1070452) — Ňɏssa Pøngjǣrdenlarp, Jun 20 '15 at 20:37

score 3 · Accepted Answer · answered Jun 20 '15 at 20:40

3

This line is wrong:

If key IsNot DBNull.Value Then

DBNull.Value is used for SQL database results, and not for registry keys. Try this instead:

If key IsNot Nothing Then

answered Jun 20 '15 at 20:40

Joel Coehoorn

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System.NullReferenceException when trying to read registry key VisualBasic

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