How to change the LOCALAPPDATA environment variable in PowerShell?

I'm trying to change the location of the %LOCALAPPDATA% environment variable in PowerShell, but the change is not taking effect.

Details of the Problem

I want to set the LOCALAPPDATA variable to a new directory (G:\AppData\Local), but after following several methods, it still shows the default location (C:\Users\username\AppData\Local) in PowerShell and other applications.

What I Tried

1. Set the environment variable using [System.Environment]::SetEnvironmentVariable():

   [System.Environment]::SetEnvironmentVariable("LOCALAPPDATA", "G:\AppData\Local", "User")
   

   • The variable should reflect the new path in the current PowerShell session.

2. Verified the change using echo $env:LOCALAPPDATA:

   • The command shows the new location, but it's not reflected in other applications.

3. Restarted Powershell:

   • Closed and reopened PowerShell, but the change is still not visible.

• While the paths of known (special) folders are reflected in environment variables, they cannot be changed that way.

  • In fact, such environment variables are volatile ones that are set by the system and seemingly override any attempts to set them as regular, persisted variables.

• Use SHSetKnownFolderPath to change the location of known folders. It must be invoked via P/Invoke with the KNOWNFOLDERID (GUID) of the target folder, which from PowerShell requires an Add-Type call with ad hoc-compiled C# code.

  • A simpler, registry-based approach (for user-specific folders only, via HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\User Shell Folders) is discouraged and not officially supported, but still seems to work in practice as of Windows 11.

Changing the path of known folder %LOCALAPPDATA% for the current user:

(
  Add-Type -NameSpace NS$PID -Name KnownFolderPath -PassThru -MemberDefinition @'
[DllImport("shell32.dll")]
public extern static int SHSetKnownFolderPath(ref Guid folderId, uint flags, IntPtr token, [MarshalAs(UnmanagedType.LPWStr)] string path);
'@
)::SHSetKnownFolderPath(
  [ref] [guid] '{F1B32785-6FBA-4FCF-9D55-7B8E7F157091}', # folder ID
  0, # flags
  [IntPtr]::Zero, # target the current user
  'G:\AppData\Local' # new path
)

Note:

• A return value of 0 indicates success.

• The change takes effect:

  • immediately, when querying the known folders via APIs.
  • on the next logon / reboot with respect to the environment variable, $env:LOCALAPPDATA.
    • Alternatively, you can forcefully kill and thereby restart all Windows shell processes, and then start a new PowerShell session; however, note that this forcefully closes all open File Explorer windows and redraws the taskbar and desktop:
      Stop-Process -Name explorer -Force

• Changing the location of a user-independent well-known folder (e.g., that of %PROGRAMDATA%) requires elevation (running with administrative privileges)

• Changing the location of a well-known folder for a different user requires obtaining an impersonation token for them via the LogonUser WinAPI function (which would similarly have to be wrapped via P/Invoke in the Add-Type call) and pass it instead of [IntPtr]::Zero above; this too requires running with elevation.