Hi there! I’m running Fairphone 4 with Android 15 (CalyxOS). Now I want to flash Ubuntu Touch (wich is official rom for FP4 :). But Ubuntu Touch installation documentation requires to have original Fairphone OS with Android 11.
Is It possible to safe (not bricking) downgrade from Calyx Android 15 to Android 11? How can I do that? I know there is some anti-rollback feature?
just DON’T RELOCK the bootloader with an older installed build than the one on witch you unlocked in the past.
on android, it is based on “Android Security Patch” at time bootloader was unlocked / relocked
Thank you so much for detailed answer! Just another detail maybe you know - could I lock bootloader after Ubuntu Touch flashing since it has official support for FP4?
sorry i know nothing about “Ubuntu Touch”. (only a few about PostmarketOS)
also i have no personnal interrest about relocking the bootloader.
if Ubuntu Touch offer the possibility of relocking,
just take attention that the relative date to be newer or the same than when you unlock.
I guess thats still correct