Acronis Cyber Protect Cloud: Installation fails with 'MainEngineThread is returning 1601 MSI'

Symptoms

Installation in Windows fails immediately upon start.

In installation logs, you find error 1601:

MainEngineThread is returning 1601 MSI

Cause

Error code 1601 indicates an issue with the Windows Installer service:

The Windows Installer service could not be accessed.

You can verify that you are facing this exact issue by trying to install another software using its MSI installer.