Impossible to create an admin user: warning an error occurred while requesting the API

I’ve been struggling for hours trying to install Strapi on my Ubuntu 20.04 server.

npx create-strapi-app@latest my-project --quickinstall

All the installation process goes smoothly but when I go to http://mydomain:1337/admin in order to create a first user I get this warning:

Warning: an error occurred while requesting the API.

I know this problem has been encountered several times but none of the suggested solutions have helped me so far.
I also found this error in the Chrome console but I’m not not sure it’s related to the my issue:

main.815f1087.js:2 Refused to connect to ‘http://localhost:1337/admin/project-type’ because it violates the following Content Security Policy directive: “connect-src ‘self’ https:”.

So I set the default contentSecurityPolicy to false in


but all I get now is a 500 (Internal Server Error).
Can someone help me ?

System Information
  • Strapi Version: 4
  • Operating System: Ubuntu 20.04
  • Database: SQLite
  • Node Version: v14.19.0
  • NPM Version: 6.14.16
  • Yarn Version: