How to force Windows to reconnect to network drive

Question

We try to access a directory which is within a network directory but get wrong results (C#/Windows):

var exists = Directory.Exists("Z:\\Sessions\\Data1");

"Z" is the network directory, "Sessions" is a directory where a recording software constantly creates directories (e.g. "Data1") and puts some data in it. It seems that Windows caches the wrong state about Data1: The method returns false. But when I access the directory via Explorer it's here. When I run the method (Directory.Exists) after accessing the directory with Explorer, it returns true. Of course I can guarantee that the directory actually exists at the first attempt.

What is the reason for this behaviour? What can I do about it?

Edit: It seems that windows could not connect the network drive to the remote computer. When I try to navigate into the directory with Explorer it automatically tries to connect the drive.

So the question changes: Is there a way to force windows to try a reconnect via .NET?

Solution: Reconnecting a disconnected network drive

Answer 1

I'm not sure which version of mpr.dll the solution link above works with, but I am using Win7 and have a slightly different version (although similar). This entry point is:

    [DllImport("mpr.dll", SetLastError = true, EntryPoint = "WNetRestoreSingleConnectionW", CharSet = CharSet.Unicode)]
    internal static extern int WNetRestoreSingleConnection( IntPtr windowHandle,
                                                            [MarshalAs(UnmanagedType.LPWStr)] string localDrive,
                                                            [MarshalAs(UnmanagedType.Bool)] bool useUI);

then:

IntPtr hWnd = new IntPtr(0);
int res = WNetRestoreSingleConnection(hWnd, <your drive path>, false);

You'll have to add your own error checking / handling.

Answer 2

I too use a remote drive and it takes a few seconds to connect, so I just wait and works every time. If it does not connect, it will send an email and I will check it.

        logger.Info("Create Z: drive ");
        System.Diagnostics.Process process = new System.Diagnostics.Process();
        System.Diagnostics.ProcessStartInfo startInfo = new System.Diagnostics.ProcessStartInfo();
        startInfo.WindowStyle = System.Diagnostics.ProcessWindowStyle.Hidden;
        startInfo.FileName = "cmd.exe";
        startInfo.Arguments = @"/C net use z: \\" + Tools.servername + @"\SHARE_NAME_HERE /user:USER_NAME_HERE PASSWORD_HERE";
        process.StartInfo = startInfo;
        process.Start();
        logger.Info("Z: drive created ");

        // wait get Z:
        int xtimestimeout = 5;
        while (!Directory.Exists(@"Z:\") & (xtimestimeout > 0))
        {
            Application.DoEvents();
            SetBalloonTip(@"Program", @"connecting... please wait");
            ShowBalloon();
            logger.Info("Creating Z:... waiting...");
            Application.DoEvents();
            System.Threading.Thread.Sleep(3000);
            xtimestimeout -= 1;
        }

        // check for sucessfull creation of Z: in server Z:\somedirectory
        if (!Directory.Exists(@"Z:\"))
        {
            SendEmail2("Oh my... help!", "drive Z: not created <<< CHECK!");
            logger.Info("Z: email sent because of not created");
        }
        logger.Info("Z: drive created successfully.");