Hello (again).
As nobody answers here, I kept googling and found another site (sorry, it seems to be not allowed posting other sites then xda site...).
Here the method is explained with Odi and pointed out that you will NOT lose any data.
So I followed this tutorial and updated my Galaxy S9 + with Odin to Android Pie (G965FXXU2CSA2).
Everything is very good so far. Mobile started and I was happy to see Android 9.0 booting.
My apps were still there. Only all app permissions and ringtones were gone.
But the bigger problem for me - MY ROOT IS GONE !!!
Can anyone help me, how to root the Galaxy S9 + Exynos G965F/DS with Android 9.0 ?!
In
this thread, it seems that there are currently some problems with S9 in rooting Android Pie... Are there any solutions or instructions how to proceed? Or is it better to wait? Is there a difference so my S9+ (plus)?
I am aware that I have lost the KNOX security through the root.
I am also aware that I do not receive any OTA updates.
I agree that I have to do any update via Odin, as long as I do not lose all settings and apps every time.
But:
Is there a way to flash only UPDATES and not always the latest complete ROM?
Is there a way to keep the ROOT, or do I have to do that again after each update?
Maybe someone will tell me...

And please forgive me, if i am already annoying and not that clever in rootin as you
Thank you !!!