I am sorry, @lottier, but perhaps we could return to your originl thread (or a new one) and add a contrbution to Document Suggestions when we have found a solution. 
My guess you have a Korean device | Korea firmware, where you require a Korean device | your Region firmware. CSC Codes for Korea: SKT, LUC, SKC, KTC
… and /or … star2lte - SM-G965N | starlte - SM-G960N
Yes, I now have a generic problem unrelated to documentation or to my original problem - I’ll stop updating here and find more a relevant location. Thanks !
Device : Samsung S9 [SM-G960F/DS]
eOS : e-1.9-q-20230310268292-stable-starlte.zip
Documentation : https://doc.e.foundation/devices/starlte/install
I ve just finished the installation on my New Second-Hand S9 Phone using the documentation linked above.
Everything went as written and I see absolutely nothing to add to this documentation.
Thank you so much 
Continuing the discussion from Samsung - Galaxy S9 - starlte - Documentation Suggestions:
Android T dev /e/os 1.15 samsung s9
(Via r 1.15)
Zip file contains recovery.img… extract amd then use heimdall with s9 in bootloader mode
Next put into recovery mode - factory reset option before sideloading with adb the complete zip
In my experience you get bootloop if no factory reset stage in recovery (of course means a lot of re setting up after).
But, can report I have working android t v1.15 on my S9
Which one do you use ? Here the recovery image for T build is not yet available.
Do you mean download mode ? I though there was no bootloader mode for samsung.
Maybe because (supposition) you didn’t get the right recovery image ?
I noticed no recovery image on the usual web page. But if you look inside the lonely zip file there is a recovery.img file inside… The one I used.
Yes download mode (not boot) with blue screen on Samsung (bixby vol-down power) heimdall the recovery.img
If you then adb sideload the whole zip in recovery mode after factory reset, all works, but need to resetup… Otherwise, when at first I tried no factory reset, the boot-loop (e bounce . forever happened after sideload and reboot).
Hope that is a little clearer
OK thank you!
I really try to find a really detailed workflow to upgrade from Q to T without data loss via sideload. Your repport here give me less hope…
Understand… I was on Q, upgraded to R (was not good), hence endeavor to try T…
Fortunately for me, I was well backed up on data before the boot loop. Fortunately no bricking as I recovered as described earlier.
But, it still did take me best part of a day to get all going again.
T is (eventually) much better. In hindsight I probably would have been better off staying on stable channel and waiting for OTA update, but, wanted to report that it is doable today, as there seemed not much testing on the forums at this early point.
Good wishes
NO, it is because the device tree have not the same organisation now…