Show MessageBox on Datagridview Checkbox before Check or UnCheck

How to show a msgbox before update the checkbox in datagridview?

Lets say I have a row with checkbox in Datagridview and the value of it is True(Checked) and I will click it. How can I show something like this first?

"Are you sure you want to uncheck this? Yes or No"

Yes = Uncheck

No = Still the same (Checked)

here is my code with the output i want but its not working

 Private Sub DataGridView3SelectAll_CurrentCellDirtyStateChanged(
      ByVal sender As Object,
      ByVal e As EventArgs) Handles DataGridView3.CurrentCellDirtyStateChanged

        RemoveHandler DataGridView3.CurrentCellDirtyStateChanged,
            AddressOf DataGridView3SelectAll_CurrentCellDirtyStateChanged

        If TypeOf DataGridView3.CurrentCell Is DataGridViewCheckBoxCell Then
            DataGridView3.EndEdit()
            Dim Checked As Boolean = CType(DataGridView3.CurrentCell.Value, Boolean)
            Dim xx As String
            xx = MsgBox("Are you sure you want to save changes?", vbYesNo)
            If xx = vbYesNo Then
                If Checked = True Then
                    Dim s As String = (DataGridView3.Columns(DataGridView3.CurrentCell.ColumnIndex).DataPropertyName)
                    Dim x As Integer
                    x = DataGridView3.CurrentCell.RowIndex
                    Dim con1 As MySqlConnection = New MySqlConnection("datasource=192.168.2.87;database=inventory;userid=root;password=admin1950")
                    Dim cmdinsert As MySqlCommand = New MySqlCommand("update stock_issuance set `" & s & "` = 1 where `" & s & "` = `" & s & "` and Month = '" & DataGridView3.Rows(x).Cells(1).Value & "'", con1)
                    con1.Open()
                    cmdinsert.ExecuteNonQuery()
                    con1.Close()
                ElseIf Checked = False Then
                    Dim s As String = (DataGridView3.Columns(DataGridView3.CurrentCell.ColumnIndex).DataPropertyName)
                    Dim x As Integer
                    x = DataGridView3.CurrentCell.RowIndex
                    Dim con1 As MySqlConnection = New MySqlConnection("datasource=192.168.2.87;database=inventory;userid=root;password=admin1950")
                    Dim cmdinsert As MySqlCommand = New MySqlCommand("update stock_issuance set `" & s & "` = 0 where `" & s & "` = `" & s & "` and Month = '" & DataGridView3.Rows(x).Cells(1).Value & "'", con1)
                    con1.Open()
                    cmdinsert.ExecuteNonQuery()
                    con1.Close()
                End If
            Else

            End If
        End If


        AddHandler DataGridView3.CurrentCellDirtyStateChanged,
            AddressOf DataGridView3SelectAll_CurrentCellDirtyStateChanged
    End Sub

You can first set ReadOnly property of column to True, then handle CellContentClick event of DataGridView this way:

Private Sub DataGridView1_CellContentClick(ByVal sender As System.Object, _
    ByVal e As DataGridViewCellEventArgs) Handles DataGridView1.CellContentClick
    If (e.ColumnIndex = 0 AndAlso e.RowIndex >= 0) Then
        Dim result = MessageBox.Show("Check Item?", "", MessageBoxButtons.YesNoCancel)
        If (result = System.Windows.Forms.DialogResult.Yes) Then
            DataGridView1(e.ColumnIndex, e.RowIndex).Value = True
        Else
            DataGridView1(e.ColumnIndex, e.RowIndex).Value = False
        End If
    End If
End Sub

To make the column ReadOnly you can use both code and designer.

To get confirm only when unchecking the cell:

Private Sub DataGridView1_CellContentClick(ByVal sender As System.Object, _
    ByVal e As DataGridViewCellEventArgs) Handles DataGridView1.CellContentClick
    If (e.ColumnIndex = 0 AndAlso e.RowIndex >= 0) Then
        Dim value = DirectCast(DataGridView1(e.ColumnIndex, e.RowIndex).FormattedValue, _
                               Nullable(Of Boolean))
        If (value.HasValue AndAlso value = True) Then
            Dim result = MessageBox.Show("Are you sure to uncheck item?", "", _
                                          MessageBoxButtons.YesNoCancel)
            If (result = System.Windows.Forms.DialogResult.Yes) Then
                DataGridView1(e.ColumnIndex, e.RowIndex).Value = False
            End If
        Else
            DataGridView1(e.ColumnIndex, e.RowIndex).Value = True
        End If
    End If
End Sub