If the computer you have installed ExtendSim on does not contain the Universal C Runtime in Windows, the following error message (or something similar) may appear while trying to launch ExtendSim (or other newer applications):

The program cannot start because api-ms-win-crt-runtime-l1-1-0.dll is missing from the computer.
Try reinstalling the program to fix this problem.

You will need to install the Universal C Runtime (CRT) update on your Windows operating system to enable newer applications (like ExtendSim) to run on a Windows OS earlier than 10. The Microsoft web site offers instructions for updating the Universal C Runtime component.