KB: Update gives error: This application requires Windows hotfix KB3140245

Solution Details

Windows Hotfix KB3140245 is simply defined by Microsoft as "Update to enable TLS 1.1 and TLS 1.2 as default secure protocols in WinHTTP in Windows".  More information on this update is available here:
Update to enable TLS 1.1 and TLS 1.2 as default secure protocols in WinHTTP in Windows
 
This article from Microsoft describes how to enable TLS 1.2:
How to enable TLS 1.2 on clients

This Knowledge Base article has steps and images (near the bottom) to check if it's enabled:
https://www.altium.com/documentation/knowledge-base/altium-designer/error-from-portal365-altium-com

To see if this hotfix is installed, you can go to "Start » Settings » Control Panel » Programs » Programs and Features" and selecting "View Installed Updates". Please confirm "Microsoft Windows Update KB3140245" is listed.  (Computers with this issue do not show this hotfix as installed.) 
 
There is a tutorial on the Support.Microsoft.com website that talks about needing to add a registry key. Please review the article here (but the next paragraph may be the best way to resolve this issue):
Update to enable TLS 1.1 and TLS 1.2 as default secure protocols in WinHTTP in Windows
 
This procedure has been used several times successfully to resolve this issue: Try using the Deployment Image Servicing and Management ("DISM") tool from Microsoft to install KB3140245. There is a good description of the process on the Microsoft "Core Team" document Blog here:
https://docs.microsoft.com/en-us/archive/blogs/askcore/how-to-use-dism-to-install-a-hotfix-from-within-windows

Tip:  When running DISM.exe, you need to change to the directory where the .cab file is before executing the dism.exe command, since that folder will not be in the Windows path environment.
 
The hotfix source file is available here:
Microsoft®Update Catalog