Create a folder within a network drive with System.IO.Directory.CreateDirectory

Question

On my local computer I created the network drive D:/ that points to \\MyComputerName\D.

On my local disk C:/ I created a folder with the name D and configured a network share with permission to everyone on that share.

Then I start Windows PowerShell ISE. My working directory is C:\Users\username

After that I create a folder with Powershell within this network drive such as

  [System.IO.Directory]::CreateDirectory("D:/Foo/Bar")

the directory Foo with his subfolder Bar will be created successfully.

Then I remove the Foo folder within D:/ and start Visual Studio 2019 with Admin Permissions.

Then I create a simple C#.NET Console Application such as

class Program
{
    static void Main(string[] args)
    {
        System.IO.Directory.CreateDirectory(@"D:/Foo/Bar");

    }
}

If I run the Console Application the directory will not be created and I get System.IO.DirectoryNotFoundException: 'Could not find a part of the path 'D:\Foo\Bar'.'

What should I do to create successfully the folder with my simple console application?

Answer 1

Fundamentally, if you run a process with elevation (as administrator), it will not see the drive mappings you've established while running non-elevated.

You can verify this as follows:

# Establish a (temporary) mapping; making it persistent makes no difference.
# Note: This assumes that the admin shares are turned on.
net use T: "\\$(hostname)\c$\Users"

# Start a new PowerShell process *elevated* (as admin)
# You'll see that it can't find drive T:
Start-Process -Verb Runas powershell '-noprofile -c Get-ChildItem T:; pause'

# Clean up
net use T: /del

---

The simplest workaround is to use the UNC path directly to create your folder.

If you don't want to hard-code that into your application or you don't want to re-create the mapping for your elevated incarnation beforehand, you'll have to find some other way to communicate the drive-mapping information from your non-elevated incarnation to your elevated one.

If all code that needs to see the mapped drive is run via PowerShell, a solution is to place net use calls in the $PROFILE file.