File.Exists returns false,Process.Start() can't start the file,But it actually exists

Question

Note : Windows Sandbox is enabled on my computer.

Console.WriteLine(File.Exists(@"C:\Windows\system32\WindowsSandbox.exe"));
Console.WriteLine(new FileInfo(@"C:\Windows\system32\WindowsSandbox.exe").Exists);

Running the above code in C# Interactive(VS is not in admin mode):

True
True

However , when I run it in a console application, (both admin mode and non-admin mode).The results are always false.

False
False

I tried Process.Start(@"C:\Windows\system32\WindowsSandbox.exe"), the console application failed(admin and non-admin) but the C# interactive succeeded.

In powershell,C:\Windows\system32\WindowsSandbox.exe successfully started the Windows Sandbox. In explorer(system32 folder): image

Could anyone explain why this could happen?

Answer 1

I'm not familiar with Windows Sandbox, but it sounds like this is an architecture issue.

On 64-bit Windows, C:\Windows\system32 is the 64-bit system directory. Explorer and PowerShell, which you say can both see C:\Windows\system32\WindowsSandbox.exe, will be 64-bit processes unless you go out of your way to run the 32-bit versions.

In a 32-bit application, the path C:\Windows\system32 gets redirected to the 32-bit system directory, C:\Windows\SysWOW64. Since you say you don't have a C:\Windows\SysWOW64\WindowsSandbox.exe file, nor can your application see (what it thinks is) a C:\Windows\system32\WindowsSandbox.exe file, that suggests that your application is built targeting 32-bit.

So, the problem is there is no 32-bit version of Windows Sandbox for your 32-bit application to run. When you change the path to calc.exe or notepad.exe your same code works because Windows provides both 32- and 64-bit versions of those executables. To get your application to run the 64-bit WindowsSandbox.exe, you can either...

• Build it targeting 64-bit, or better yet...
• Have it execute the path C:\Windows\sysnative\WindowsSandbox.exe. sysnative is a special alias that allows 32-bit applications to reference the native (64-bit) system directory without redirection.

As for why Visual Studio is able to see C:\Windows\system32\WindowsSandbox.exe, I can't really explain that. It would depend on what version you're using, but it's my understanding that continues to be a 32-bit application, although it would make sense that some components are 64-bit. As for whether components such as the debugger would run as the same architecture as the OS or the application being built, I really don't know.

Answer 2

From the documentation:

The Exists method returns false if any error occurs while trying to determine if the specified file exists. This can occur in situations that raise exceptions such as passing a file name with invalid characters or too many characters, a failing or missing disk, or if the caller does not have permission to read the file.

One way of seeing what's happening is to just try to read the file (e.g. with File.OpenRead). I'd be surprised if that succeeds - but if it fails, the exception should give you more information. Also check from the call what identity is used when running the command (i.e. cmd whoami, etc.)