When using a virtualenv and if you only need to improve deals additional to your virtualenv, you might want to do: all classes and interfaces within the superclass hierarchy (e.g. see Java class is present in classpath but startup fails with Mistake: Could not discover or load principal class) Mimic https://event95172.blogsidea.com/40186187/not-known-details-about-uninterruptible-power-supply-definition