Thank you, Mustafa.
In the 24.4 db I'm not able to open the pages you mentoined due to the problems described in my initial post.
In my 18.6 db the "Profiles (Roles)" page was a bit messy.
There were some "duplictes". I think because of some older upgrdes.
So I removed all "user-created" profiles, but one that comes with an extension.
In "User Personalization List" there are entries from some, but not all users.
I also deleted all records from "Personalized Pages".
And I also deleted all companies, but CRONUS AG (to speed up the migration).
But unfortunately the result is still the same.
I get the empty role center, menu and pages for all users.
Also for newly created super users.
I also think that it's a "data problem" and not a problem of the migration process.
I hope you or someone else has an idea.
Thanks again & have a great weekend
Tobias
Here are the cleaned-up Profiles (Roles) from my 18.6 db.