Rasa X any version is not yet compatible with Rasa 3.X may be available end of this quarter as per Rasa Team.
If you are trying to install Rasa X you can use the following combination Rasa X 0.39.3 with Rasa 2.x or you can follow this thread : Rasa X runs with several Errors & Warnings - #7 by vio_lovis
If you having any further doubt please tag me.