Windows

This page covers proxy environment variables on Windows, and how to fix PATH variables that stop expanding and "untrusted mount point" errors in SSH sessions.

Configuration#

Set the proxy with user-level environment variables.

Configure a proxy#

Set the proxy environment variables for the current user:

[System.Environment]::SetEnvironmentVariable("http_proxy", "http://127.0.0.1:7890", "User")[System.Environment]::SetEnvironmentVariable("https_proxy", "http://127.0.0.1:7890", "User")

Troubleshooting#

These problems commonly appear after editing PATH and in SSH sessions.

PATH variables stop expanding#

Cause: the PATH value type was changed to REG_SZ. References like %USERPROFILE% only expand when the value type is REG_EXPAND_SZ. [Environment]::SetEnvironmentVariable writes REG_SZ, so changing PATH with it once turns every %VAR% into a literal. The editor in System Properties also expands them into absolute paths.

PATH lives in two registry keys, merged at logon with the machine scope first and the user scope after it:

HKLM\SYSTEM\CurrentControlSet\Control\Session Manager\Environment   machineHKCU\Environment                                                    user

Set the type explicitly when you change PATH. $v is the new PATH value:

Set-ItemProperty -Path "HKCU:\Environment" -Name Path -Value $v -Type ExpandString

Check the type and the raw value:

$uk = "HKCU:\Environment"(Get-Item $uk).GetValueKind("Path")                                 # should be ExpandString(Get-Item $uk).GetValue("Path", "", "DoNotExpandEnvironmentNames")  # should contain %USERPROFILE%

Notes:

• Changes only apply to terminals opened afterwards.
• Third-party installers often write PATH with SetEnvironmentVariable, so installing a program can flip the type back to REG_SZ. Check again after installs.
• Use %SystemRoot% for system directories and %JAVA_HOME%, %CUDA_PATH% for the JDK and CUDA, so switching versions means changing one variable. %CUDA_PATH% follows the active version. Avoid version-pinned variables like %CUDA_PATH_V12_9%.
• Do not write Program Files as %ProgramFiles%. In 32-bit processes it expands to Program Files (x86).

SSH sessions report an untrusted mount point#

The path cannot be traversed because it contains an untrusted mount point.

Cause: since Windows 11 24H2, SSH sessions no longer follow some symbolic links and junctions. Local terminals are unaffected. The same configuration works on Windows 10 22H2, so nothing is misconfigured, and fsutil behavior set SymlinkEvaluation does not help.

Choose the fix by what is blocked:

• A junction is blocked: recreate it with mklink /J. Junctions made by the native API are followed:

  powershell

  cmd /c rmdir "<link path>"cmd /c mklink /J "<link path>" "<real target>"

• A command installed by WinGet is blocked: everything under WinGet\Links is a symbolic link. Put the real directory %LOCALAPPDATA%\Microsoft\WinGet\Packages\<package ID> at the front of the user PATH. To write PATH, see PATH variables stop expanding.

• pnpm install fails: pnpm's node_modules is built from junctions, so installing over SSH always fails. Install and upgrade locally or over Remote Desktop. Using what is already installed over SSH works.