ITKab/ endpoint ops

Windows Installer

1605

This action is only valid for products that are currently installed.

  • Symbolic name ERROR_UNKNOWN_PRODUCT
  • Also seen as 0x80070645
  • Updated 2026-08-20

Needs attention

What it means

You asked Windows Installer to uninstall or reconfigure a product GUID that is not registered on this device. In a fleet, this normally means the uninstall already ran, or the GUID belongs to a different version of the product.

Real causes

  • The application is not installed on that device at all.
  • The product GUID changed between versions and your uninstall command still references the old one.
  • The product is installed per-user under a different profile than the one the uninstall is running in.

What to do

  1. List what is actually registered: Get-ItemProperty HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\* | Select-Object DisplayName, DisplayVersion, PSChildName
  2. Check the 32-bit hive too: HKLM:\SOFTWARE\WOW6432Node\Microsoft\Windows\CurrentVersion\Uninstall\*
  3. Treat 1605 as success in an uninstall deployment. The end state you wanted, the product being gone, is already true.

Where to look

  • Application event log, MsiInstaller source

Checked against Microsoft documentation. Last reviewed 2026-08-20.

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