C# - Get Process Path From Management Watcher

I know how to get the process names that start on Windows, however, I am unable to get the process paths of the names...

Here's my attempt:

                var mgmtWtch = new ManagementEventWatcher("Select * From Win32_ProcessStartTrace");
                mgmtWtch.EventArrived += new EventArrivedEventHandler(mgmtWtch_EventArrived);

 private void mgmtWtch_EventArrived(object sender, EventArrivedEventArgs e)
            String ProcessName = e.NewEvent.Properties["ProcessName"].Value.ToString();
            Process n = Process.GetProcessById(Convert.ToInt32(e.NewEvent.Properties["ProcessID"].Value));
            String ProcessPath = n.MainModule.FileName;
                MessageBox.Show(ProcessName + "\n" + ProcessPath);

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When I start a process, it returns an exception on GetProcessById() that "No process with pid #### exists", even though it does. Maybe something to do with this being a 32 bit application and I'm running x64 processes? It did work with one x86 process. Other times it will throw an exception "Access Denied" on n.MainModule.FileName...

Hoping someone knows a better way to do this.

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hintcoConnect With a Mentor Commented:
This is the best way to get the process path.
try it.
                    //Get Command Line from the process
                    string wmiQuery = string.Format("select CommandLine from Win32_Process where Name='{0}'", p.ProcessName + ".exe");
                    ManagementObjectSearcher searcher = new ManagementObjectSearcher(wmiQuery);
                    ManagementObjectCollection retObjectCollection = searcher.Get();
                    foreach (ManagementObject retObject in retObjectCollection)
                        if (retObject["CommandLine"] != null)

                            MessageBox.Show("Command_Line: {0}", retObject["CommandLine"].ToString());

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and let's try to run your application as administrator.
SteveDXLAuthor Commented:
Ah yes definitely seems like the issue is not being able to find 64bit processes from a 32 bit application. Compiling this app as a a 64 bit or "Any CPU" will cause a ton of other problems , because its intended to monitor a 32 bit process.

Is what you are trying todo here, get running processes on the computer? Does it have to be from the Management Watcher?
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Here is another way to do it, probably allowing System.Diagnostics and Bit of LINQ to help you:-
var lstPaths = Process.GetProcesses().Select(p => p.Modules[0].FileName);

foreach(var item in lstPaths)
 //do your magic here.               

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Two things to note however:-
1. Run your app(even VS) as an administrator
2. For 64-bit processes you need to compile the app with Target as x64.
SteveDXLAuthor Commented:
Thanks to everyone for offering their insight!

@hintco, this appears to be the best solution. Last night I came up with

const string wmiQueryString = "SELECT ProcessId, ExecutablePath, CommandLine FROM Win32_Process";
               using (var searcher = new ManagementObjectSearcher(wmiQueryString))
               using (var results = searcher.Get())
                   var query = from p in Process.GetProcesses()
                               join mo in results.Cast<ManagementObject>()
                                   on (int)(uint)e.NewEvent.Properties["ProcessID"].Value equals (int)(uint)mo["ProcessId"]
                               select new
                                              Process = p,
                                              Path = (string) mo["ExecutablePath"],
                                              CommandLine = (string) mo["CommandLine"],
                   foreach (var item in query)

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but your code seems to be much cleaner and less taxing.

Thanks again to all!
SteveDXLAuthor Commented:
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