"changes that are not yet reflected in a migration" message despite of "No changes detected" in makemigrations

Hi,

I recently upgraded from Django 2 to Django 3.2.

Everything works fine but when I execute “migrate” as a manage.py command, it always says “Your models in app(s): ‘admin’, ‘auth’, ‘base’, ‘contenttypes’, ‘sessions’ have changes that are not yet reflected in a migration, and so won’t be applied.
Run ‘manage.py makemigrations’ to make new migrations, and then re-run ‘manage.py migrate’ to apply them.”

If I execute “makemigrations” commands I always get “No changes detected”.

I downgrade to Django2, the message is gone.

I have every mentioned app on my INSTALLED_APPS variable in settings. As you can see only ‘base’ app is one of mine, the rest are default Django apps.

I am using Oracle 19 database that can not be recreated.

I hope you can help me or give me some ideas of what is happening and why am I receiving that message from “migrate” command.

Thank you in advance,
Ismael.