Installing .NET Framework 4.7.1 on Windows Server 2012 as a prerequisite for patching Exchange 2016 CU8 to CU12 remains stuck at: “File security verification: All files were verified successfully.”

Problem

You’re attempting to patch an Exchange Server 2016 CU8 environment to the latest CU12 and one of the prerequisites is to install .NET Framework 4.7.1 so you proceed to download the offline installer executable, run the install but notice that it remains stuck at:

File security verification:

All files were verified successfully.

Solution

You’ll notice that even attempting to hit the Cancel button to cancel the install would present the rollback status indefinitely.  What I ended up doing was restart the server to stop the installer and the solution to upgrading the .NET Framework 4.6 to the required 4.7.1 is to download the MSU packages at the following URL:

https://www.catalog.update.microsoft.com/Search.aspx?q=KB4033369

Run the two MSU files:

Then use the following cmdlet to verify the version of .NET Framework after a server restart:

Get-ItemProperty -Path "HKLM:SOFTWARE\Microsoft\NET Framework Setup\NDP\v4\Full" | Format-List

Before upgrade:

After upgrade:

.NET Framework Version Table: