Acronis True Image 2019 is currently installed on a Mac.
You launch the program and it detects that a newer version of the software is available.
When you try to download and install it, an error occurs: "For security reasons, updates that downgrade versions of the application are not allowed".
Known issue with the live update.
This issue is resolved in the product, please update to the latest build. See this article for instructions: Acronis True Image 2019: how to update to the latest build (Mac)