Install Rasa error

Welcome and Hello @Cristiano please downgrade the pip version to 20.2.3 pip install 20.2.3

It will install with in few seconds, If you need to install rasa and rasa open source please follow this thread as per your reference: Rasa X runs with several Errors & Warnings - #2 by nik202

Good Luck! I hope this will help you and solve your issue.