SolarWinds Platform installer is failing during install or upgrade with error Object reference not set to an instance of an object

This is a known issue.

The user used to run the installer has a $ symbol, and is failing to build a correct LiteralPath due to "$" in username (logged into windows). 

Checking Administration log of Installer folder:

INFO  (null) SolarWinds.ReleaseManagement.Model.Security.PowerShellService - Invoking: 'powershell.exe -ExecutionPolicy RemoteSigned -Command "Import-Module Microsoft.PowerShell.Security -RequiredVersion 3.0.0.0; Get-AuthenticodeSignature -LiteralPath \"C:\Users\$cpace\AppData\Local\Temp\SolarWinds\SWA\wyu1o3rl.0up.psd1\" "'
ERROR (null) SolarWinds.Administration.DataProviders.CachingProductCatalogProvider - Cannot read cached Product Catalog. System.ComponentModel.Win32Exception (0x80004005): powershell.exe exited with code 1. Output:  StdErrOutput: Get-AuthenticodeSignature : File C:\Users\AppData\Local\Temp\SolarWinds\SWA\wyu1o3rl.0up.psd1 was not found.
At line:1 char:71
+ ... on 3.0.0.0; Get-AuthenticodeSignature -LiteralPath "C:\Users\$cpace\A ...
+                 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : ObjectNotFound: (:) [Get-AuthenticodeSignature], FileNotFoundException
    + FullyQualifiedErrorId : SignatureCommandsBaseFileNotFound,Microsoft.PowerShell.Commands.GetAuthenticodeSignature 
   Command


The two in green above didn't match so it couldn't read the file.

As  is a special symbol in PowerShell we are evaluating paths with dollar signs wrong 

This issue is addressed in SolarWinds Platform 2026.1. Consider upgrading your environment. If you cannot upgrade, use the workaround below.

Workaround: Change TEMP Environment Variable to a Path Without $ Character

Steps to Change TEMP Environment Variable:

1. Open the Environment Variables window in Windows: Control Panel -> All Control Panel Items -> System -> Advanced System Settings -> System Properties > ‘Advanced’ tab > Environment Variables 
2. Under User variables or System variables, locate the variables named TEMP and TMP.
3. Edit both variables to point to a new folder path that does not contain the $ character. For example:
   C:\Temp or D:\Temp

4. Create the new folder if it does not exist.
5. Click OK to save changes and close all dialogs.
6. Restart the system or log off and log back in to apply the changes.
7. Retry running the Offline Installer.