Guard MSI UpgradeCode lookup against missing registry key

[Tom Plant (pl4nty)]

Description

Get-ADTApplication's begin block builds an MSI UpgradeCode lookup table with an unguarded Get-ChildItem on HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion\Installer\UpgradeCodes. On machines where that key does not exist (e.g. clean images / Windows Sandbox with no MSI-registered upgrade codes), Get-ChildItem throws:

Cannot find path 'HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion\Installer\UpgradeCodes' because it does not exist.
FullyQualifiedErrorId : PathNotFound,Microsoft.PowerShell.Commands.GetChildItemCommand

Because this happens in the begin block, it aborts the entire function and every caller — including Uninstall-ADTApplication, as seen in the reported stack trace.

The fix adds -ErrorAction Ignore to that Get-ChildItem, matching the pattern already used a few lines down for the uninstall-key enumeration. When the key is absent the pipeline yields no items, the scriptblock's begin/end blocks still run, and $msiUpgradeCodeLookupTable is simply an empty dictionary. Downstream indexing ($msiUpgradeCodeLookupTable[$appMsiGuid]) already returns $null for GUIDs that are not present, so behaviour is unchanged for the common case and no longer throws for the empty case.

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• General code cleanup (non-breaking change which improves readability)

Checklist

• I am pulling to the main branch
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have tested my changes to prove my fix is effective
• I have tested that the module can build following my changes
• I have made sure that any script file-encoding is set to UTF8 with BOM, i.e. unchanged.

How Has This Been Tested?

Not yet run against a live host — pwsh is unavailable in the CI/dev environment used here. The change is a single-parameter addition consistent with the existing -ErrorAction Ignore usage in the same function. Recommended verification: on a machine lacking the Installer\UpgradeCodes registry key, confirm Get-ADTApplication (and Uninstall-ADTApplication) now complete without a PathNotFound error and still return installed applications.

🤖 Generated with Claude Code

https://claude.ai/code/session_01XLNM98Nd3HZLTWFatRVgB1

---

Generated by Claude Code

[Mitch Richters (mjr4077au)]

Thanks mate, didn't even consider the possibility of this when I put this in a few weeks ago!