How to Close Console Application Gracefully on Windows Shutdown

Question

I am trying to close my vb.net console app gracefully when windows shutdown occurs. I have found examples that call the Win32 function SetConsoleCtrlHandler that all basically

Answer 1

    If Not SetConsoleCtrlHandler(AddressOf Application_ConsoleEvent, True) Then

This is the statement that gets you into trouble. It creates a delegate instance on-the-fly and passes it to unmanaged code. But the garbage collector cannot see the reference held by that unmanaged code. You'll need to store it yourself so it won't be garbage collected. Make that look like this:

Private handler As ConsoleEventDelegate

Sub Main()
    handler = AddressOf Application_ConsoleEvent
    If Not SetConsoleCtrlHandler(handler, True) Then
       '' etc...

The handler variable now keeps it referenced and does so for the life of the program since it is declared in a Module.

You cannot cancel a shutdown btw, but that's another issue.