Question

I’ve built a program in C# Windows Forms, now on the first load up it tries to create scheduled tasks. If it raises an exception and it’s in main computer then this is the first time the softwere loads (you can intall this program on many computers but one computer is the main with the scheduled tasks).

I’ve tried this program on many computers and it worked perfectly (XP-SP1/2, Vista-SP1/2, Win7), now when I try to install it on a limited user (on Win XP Pro SP2) it tries to create the scheduled tasks. I get an Argument Null Reference and when I enter the admin user, it installs the scheduled task on the admin user and won’t run if the limited user is logged in (which is 99.9% of the time) .Why do I get this exception? I’ve looked for hours on the code searching for the reason of this exception but I can’t find it!

Thanks a lot!

Amit

MainOrSec = true;

User and Pass are public variables whice return from FirstTimeUp.

private bool CreateNoExit()
        {
            try
            {
                RegistryKey key = Registry.CurrentUser;
                key = key.OpenSubKey("Crm");
                MainOrSec = Convert.ToBoolean(AESIMP.Decrypt((string)key.GetValue(AESIMP.Encrypt("MorS"))));
            }
            catch (ArgumentNullException)
            {
                MainOrSec = true;
            }
            if (MainOrSec)
            {
                ScheduledTasks sc = new ScheduledTasks();
                Task task;
                try
                {
                    task = sc.CreateTask("NoExit");
                    FirstTimeUp f = new FirstTimeUp(this);
                    f.ShowDialog();
                }
                catch (ArgumentException)
                {
                    return false;
                }
                if (!CreatT)
                    return false;
                task.ApplicationName = @"C:\Program Files\Triffon\Crm Setup
2.0.0002\noexit.exe";
                task.Comment = "Check For no exit on the database.";
                task.SetAccountInformation(User, Pass);
                task.IdleWaitMinutes = 10;
                task.Triggers.Add(new DailyTrigger(5, 0));
                try
                {
                    task.Save();
                    task.Close();
                    sc.Dispose();
                }
                catch (COMException ex)
                {
                    MessageBox.Show(ex.Message);
                    return false;
                }
                return true;
            }
            return false;
        }

Answer 1

OK, so if you get an exception, the best thing to do is to run your program under Visual Studio’s debugger so you can see exactly where the exception is called. Here, Ctrl-Alt-E is your friend: turn on the checkbox in the “Thrown” column next to “Common Language Runtime Exceptions” and you’ll break to the debugger no matter what.

If you are testing your application on a user’s computer without Visual Studio then you have some other options. One (if you’re using Pro and above) is to run the Remote Debugger on the remote PC. Then you can attach to the running program and see the exception.

If you don’t have Pro, or can’t easily use the remote debugger, then it is definitely worth using a decent logging framework like log4net to make sure that all exceptions are caught, trapped, and written to a log file. Frankly no production application should be released until this is done.

When you’ve done this, take a careful look at the exception trace to see where the problem is caused. I’d be willing to bet that that ScheduledTasks class is throwing an exception somewhere that you’re not expecting.

Finally, you’ll be getting downvotes because the culture here is “we’ll help if you let us know everything we need to know to help.” There’s been a couple of requests in the comments for the full stack trace, which hasn’t appeared, so people here will consider that rude, I’m afraid.