Setting a textbox property value within a catch block - vb.net

Question

Using VS 2013 VB.net for my ClickOnce application. I've got a function which verifies database functionality and the guts are wrapped in a Try Catch. A portion of my Catch block looks like this:
Catch ex As Exception When Err.Number = "5"
My.Application.Log.WriteException(ex)
If My.Settings.g_blnDebugMode Then
MessageBox.Show(Err.Number & " " & ex.ToString, "Exception Error")
End If
If Err.Description.Contains("The specified table does not exist") Then
MessageBox.Show("Selected file is not a valid database.", "Exception Error")
ElseIf Err.Description.Contains("The specified password does not match the database password.") Then
MessageBox.Show("The specified password does not match the current database password.", "Exception Error")
End If
Return False
What I want to do is, clear two different fields based on the two custom error messages at the bottom. Something like TextBox1.Text = "" or TextBox2.Text = "" depending on which error is thrown (invalid password or invalid database). My problem is that I don't seem to be able to set them directly or set the value of a module or global variable from within the catch block.
Error is:
Cannot refer to an instance member of a class from within a shared method or shared member initializer without an explicit instance of the class.
If it's possible how can I work around this and set my TextBoxes based on the results in the Catch block?

Answer 1

Usually the method to achieve what you are trying is to use a second a catch block
Catch ex As Exception When Err.Number = ""
MessageBox.Show(ex.Message)
FlushTextBox1();
Catch ex As Exception When Err.Number = ""
MessageBox.Show(ex.Message)
FlushTextBox2();
The error is likely appearing because the try-catch block is inside a Shared method. What that means is, the change in the value of TextBox will be repeated for all instances of the class. If you want the TextBox to behave like this, add the Shared keyword to its own declaration and remove it from the Sub's declaration. If you don't want this behaviour at all, just remove the Shared keyword. For more information on the error check the MSDN article
Alternatively you can call a local function (as shown in code) FlushTextBox1() to change the value of the TextBox outside the Sub.