I guess that your FME installation doesn't contain Python 2.7 interpreter which is deprecated in FME 2019+. Try setting "3.*" to the Python Compatibility parameter in the Navigator window.
If you need to still use Python 2.7 for some reason, you have to install it while you install FME Desktop.
We use 3 different kinds of cookies. You can choose which cookies you want to accept. We need basic cookies to make this site work, therefore these are the minimum you can select. Learn more about our cookies.