@luksus Ok, so, with yours steps and with dev system image version, latest OTA update work and i can use my phone normally. Thank a lot for your time and your help !

@luksus The downloaded update size something like 560Mb.

@luksus When i hit reboot After OTA update download is finish, device reboot automatically on recovery and UBports logo appears with the message "installing update". After that device reboot and it reboot automatically on bootloader again and again.

@luksus Ok, so i try again to install UT with images you give me in link.
I can boot on recovery manually. Just after installation i download and install lastest OTA update and after reboot, boot on UT again is impossible.
i don't know if i'm doing something wrong

@luksus I think you don't need to have Android to unlock bootloader. Without Android you can unlock bootloader with this adb command : "fastboot flashing unlock" and to lock fastboot "fastboot flashing lock".

@luksus I don't now if prior OTA updates works, it's the first time i install UT on my FP3 since OTA updates works. I have try to boot manually on recovery mode but dosn't work. I have the message "error!" with android logo. After UT installation if i lock bootloader, i can't boot on the OS. Do you now if it's normal ?

@luksus i'm still on default channel "developpement". Do i have to change for "candidate" channel ?

Hi !
In my case, after UT reboot to finish the lastest OTA update, my phone don't want boot to UT again. My FP3 reboot always on fastboot mode.

@luksus Ok, thanks, i will try this

@luksus
The artifacts from the master branch. I will retry to download and flash the last one from the master branch and see what happen.

Hi ! Firstly, good job for your work, awesome to finally have UT on FP3. Thanks
I have downloaded the last artifacts.zip and flash my FP3 and everything work well. But, when i update my phone to the last version offered of UbuntuTouch (version 91) and reboot my FP3 to done the update, the phone boot automatically on recovery.
Have seen on ubuntu_updater.log this message "/sbin/system-image-upgrader[284]: SYSTEM PARTITION: not found".
someone knows how to fix this problem ?