Process.Start in C# The system cannot find the file specified error

Question

This is a silly and tricky issue that I am facing.

The below code works well (it launches Calculator):

ProcessStartInfo psStartInfo = new ProcessStartInfo();
psStartInfo.FileName = @"c:\windows\system32\calc.exe";

Process ps = Process.Start(psStartInfo);

However the below one for SoundRecorder does not work. It gives me "The system cannot find the file specified" error.

ProcessStartInfo psStartInfo = new ProcessStartInfo();
psStartInfo.FileName = @"c:\windows\system32\soundrecorder.exe";

Process ps = Process.Start(psStartInfo);

I am able to launch Sound Recorder by using Start -> Run -> "c:\windows\system32\soundrecorder.exe" command.

Any idea whats going wrong?

I am using C# in Visual Studio 2015 and using Windows 7 OS.

UPDATE 1: I tried a File.Exists check and it shows me MessageBox from the below code:

if (File.Exists(@"c:\windows\system32\soundrecorder.exe"))
{
    ProcessStartInfo psStartInfo = new ProcessStartInfo();
    psStartInfo.FileName = @"c:\windows\system32\soundrecorder.exe";

    Process ps = Process.Start(psStartInfo);
}
else
{
    MessageBox.Show("File not found");
}

Answer 1

Most likely your app is 32-bit, and in 64-bit Windows references to C:\Windows\System32 get transparently redirected to C:\Windows\SysWOW64 for 32-bit apps. calc.exe happens to exist in both places, while soundrecorder.exe exists in the true System32 only.

When you launch from Start / Run the parent process is the 64-bit explorer.exe so no redirection is done, and the 64-bit C:\Windows\System32\soundrecorder.exe is found and started.

From File System Redirector:

In most cases, whenever a 32-bit application attempts to access %windir%\System32, the access is redirected to %windir%\SysWOW64.

---

[ EDIT ] From the same page:

32-bit applications can access the native system directory by substituting %windir%\Sysnative for %windir%\System32.

So the following would work to start soundrecorder.exe from the (real) C:\Windows\System32.

psStartInfo.FileName = @"C:\Windows\Sysnative\soundrecorder.exe";