If you encounter the similar issue. I fixed it by upgrading the version to 4.10.12. Btw, 4.0.6 and 4.1.8 don’t work for me.
And if you directly upgrade from 4.0.0 to 4.1.1+. Don’t miss the following setting, this is only mentioned in v4.1.8 migration guide.
You have to set jwtSecret in config/plugin.js
Strapi no longer populates default values for the admin JWT in
config/admin. Initial values are generated and stored in the .env file during project creation. Strapi no longer passes secrets to non-development environments, requiring users to set the secrets purposefully.