Acronis Ransomware Protection: installation on Windows 8.1 fails with "Error 5100"

Symptoms

You are installing Acronis Ransomware Protection on Windows 8.1.

Installation fails with this error message:

Error 5100
Update corresponding to KB2919355 needs to be installed before you can install this product on Windows 8.1 or Windows Server 2012 R2.

Cause

Acronis Ransomware Protection requires .NET 4.6.1 to be installed on the computer and tries to automatically install it. However, the installation may fail if the latest Windows Updates have not been installed.

Solution

1. Download and install Update for Windows KB2919442. Although this update is marked as 'update for Windows Server 2012' it can be installed on Windows 8.1 and is required for further steps.
2. Download and install Windows 8.1 Update for x64-based Systems KB2919355.
3. Re-attempt installation of Acronis Ransomware Protection.