Environment variables not being set correctly

Hello Snookred,

Since this is a public forum, we will hide your personal identifiable information, and I have sent that image of yours containing your personal identifiable information in a private message so we can work together to resolve the issue.

Thanks for the detailed post and screenshots. Please note that Windows 10 reached end of support on October 14, 2025 (details). You can still try these steps.

A value of "SYSTEM" usually means %USERNAME% was expanded under the SYSTEM account instead of your own, or something is overriding it. Two quick questions:

• Is "TEMP" or "TMP" also defined under System variables?
• Did you sign out and back in after making the change?

Step 1: Check the stored values In a normal (non-admin) Command Prompt, run:

reg query HKCU\Environment

reg query "HKLM\SYSTEM\CurrentControlSet\Control\Session Manager\Environment"

Under Environment, "TEMP" and "TMP" should be REG_EXPAND_SZ. Any system-level entry that uses %USERNAME% will resolve to "SYSTEM".

Step 2: Check for a Command Prompt AutoRun entry

reg query "HKCU\Software\Microsoft\Command Processor" /v AutoRun

reg query "HKLM\Software\Microsoft\Command Processor" /v AutoRun

If either one returns a value, it might be changing TEMP/TMP. (cmd – AutoRun)

Step 3: Re-create the variables

• Go to "System Properties" > "Advanced" > "Environment Variables".
• Delete "TEMP" and "TMP" under "User variables for David".
• Add them again with the value T:\Temp\%USERNAME%.
• Sign out, sign back in, and run set again.

Please share what Steps 1 and 2 return so we can narrow this down.

Looking forward to your update.

By the way, I am aware the Windows 10 reached end of support. However, this computer is not able to run Windows 11 and it still works pretty good. It does occur to me that this problem may not be unique to Windows 10. Like I said, given my intentions it is not causing any serious problem.

Regarding Step 3: Deleting, then recreating TEMP & TMP environment variables and then rebooting the computer did not result in any change of behavior regarding this matter.

This is something that I've been doing on my Windows computers for decades now. It is part of the initial setup that I do which in this case was years ago. I do also change the values under System Variables but in that case I did not use any variable. I simply changed both to "T:\Temp\Windows". I've certainly signed out and back in many times since I did this but I don't remember when the next sign out was done in relation to the change.

Regarding Step 1: I substituted "MyName" for the actual user name which you redacted.

C:\Users\MyName>reg query HKCU\Environment

HKEY_CURRENT_USER\Environment

OneDrive    REG_EXPAND_SZ    C:\Users\MyName\OneDrive

Path    REG_EXPAND_SZ    %USERPROFILE%\AppData\Local\Microsoft\WindowsApps;

TEMP    REG_EXPAND_SZ    T:\Temp\%USERNAME%

TMP    REG_EXPAND_SZ    T:\Temp\%USERNAME%

OneDriveConsumer    REG_EXPAND_SZ    C:\Users\MyName\OneDrive

C:\Users\MyName>reg query "HKLM\SYSTEM\CurrentControlSet\Control\Session Manager\Environment"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Environment

ComSpec    REG_EXPAND_SZ    %SystemRoot%\system32\cmd.exe

DriverData    REG_SZ    C:\Windows\System32\Drivers\DriverData

IOLIBS    REG_SZ    T:\$MarsApps\darktable\lib\libgphoto2_port\0.12.2

NUMBER_OF_PROCESSORS    REG_SZ    8

OS    REG_SZ    Windows_NT

Path    REG_EXPAND_SZ    %SystemRoot%\system32;%SystemRoot%;%SystemRoot%\System32\Wbem;%SYSTEMROOT%\System32\WindowsPowerShell\v1.0\;%SYSTEMROOT%\System32\OpenSSH\

PATHEXT    REG_SZ    .COM;.EXE;.BAT;.CMD;.VBS;.VBE;.JS;.JSE;.WSF;.WSH;.MSC

PROCESSOR_ARCHITECTURE    REG_SZ    AMD64

PROCESSOR_IDENTIFIER    REG_SZ    Intel64 Family 6 Model 94 Stepping 3, GenuineIntel

PROCESSOR_LEVEL    REG_SZ    6

PROCESSOR_REVISION    REG_SZ    5e03

PSModulePath    REG_EXPAND_SZ    %ProgramFiles%\WindowsPowerShell\Modules;%SystemRoot%\system32\WindowsPowerShell\v1.0\Modules

TEMP    REG_SZ    T:\Temp\Windows

TMP    REG_SZ    T:\Temp\Windows

USERNAME    REG_SZ    SYSTEM

windir    REG_EXPAND_SZ    %SystemRoot%

ZES_ENABLE_SYSMAN    REG_SZ    1

Regarding Step 2:

C:\Users\MyName>reg query "HKCU\Software\Microsoft\Command Processor" /v AutoRun

ERROR: The system was unable to find the specified registry key or value.

C:\Users\MyName>reg query "HKLM\Software\Microsoft\Command Processor" /v AutoRun

ERROR: The system was unable to find the specified registry key or value.

Regarding Step 3:

In order to sign out and then back in I'll need to answer in a subsequent post.