Official LineageOS 21 for FP5

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21

Have you given the documentation at LineageOS a try?

I found these pretty straight forward when I installed LineageOS on my FP5.
Granted I was still lucky that my FP had a FPOS based on Android 13 when I followed this. It seems a little bit more hassle if you already have FPOS based on Android 14.

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22

Which I do. I try to stay as up to date as possible.

23

Since most of the steps that are required are all written out pretty clear by others (Fairphone and LineageOS), I’ll just point you to the documentation I would use to achieve the installation of LineageOS on a FP5 that has already A14 installed.

To downgrade A14 to A13, which is at the time of writing a prerequisite to install LineageOS, you can follow the Install FairphoneOS manually guide from Fairphone.

  • Be certain to have a backup of all your important data because this step will wipe all your data from your device.
  • Make sure to download the A13 version offered on the page.
  • Go through the steps “flashing with fastboot”. This will allow you to downgrade from A14 to A13.
    • Remarks:
      • Be sure to have a backup from all your data as “flashing with fastboot” will wipe all your data.
      • To me the step on how to install fastboot seems to be missing here either you follow the guide on Lineage on how to install adb and fastboot or if you are on any Linux distro you can use your package manager to install fastboot, which is often bundled with adb in the package “platform-tools”.
      • If you are somewhat familiar with scripts, there seems to be a dry run and data wipe switch in the script Fairphone provides. By setting data wipe to false and dry run to true, you should be able to make a test run without making changes to your device
      • To me it is not entirely clear if the script to install FPOS with fastboot also locks the bootloader again, so it is possible you have to unlock the bootloader again when installing LineageOS.

From there you can follow the documentation from LineageOS to install LineageOS.

EDIT: I just see @hairyfred already posted this information for the downgrade a few post above this one. Maybe he can provide more feedback since he has executed those steps.

24

My understanding was, that the FP5 has a rollback protection. Doesn’t this cause trouble when downgrading to an older android version? As Fairphone describes it on their official page it should work, but I don’t understand what the rollback protection then does?

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no problem as long as you dont lock the bootloader

26

So if I use the official documentation from Fairphone to downgrade e.g. from A14 to A13, I need to make sure that I do lock the bootloader, even if that is not mentioned on the support site although it mentions the option to downgrade?

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Dont lock the bootloader is what I said

Locking the bootloader after downgrading security patch level will brick your phone.

Btw which FP instructions are you referring to?

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Just to also to emphasise

DO NOT LOCK THE BOOTLOADER UNLESS YOU KNOW WHAT YOUR DOING

Its not needed for the downgrade, if you encounter issues, try running the scripts on linux, I had better luck there :slight_smile:

29

Sorry, I should have been more clear. I was referring to the post directly above mine:

And a bit below in the same post

That confused me, because I was also under the impression that locking the bootloader is not possible after downgrade.

If you check out Install FairphoneOS manually, it states that you can use the fastboot method to downgrade:

“Works regardless of what version you are on. Can be used to downgrade to an older version (for example: Android 13 → Android 11).”

I would have expected a warning about locking the bootloader here. In the linked documentation about unlocking the bootloader, there is a warning:

“If you install an OS with an older security patch level than your previous OS, Android’s roll-back protection might brick your device when locking the bootloader!”

Why do they write “might brick your device”?

So my takeaway from this is: After using the script to downgrade to A13, check the bootloader state before rebooting.
Do I need to reboot at all, or can I start installing LOS when I’m in fastboot mode anyway?

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I would think the installation instructions in the LOS wiki are clear!?

Screenshot_20240930-225635_Fennec
Screenshot_20240930-225635_Fennec2700×1224 270 KB

31

So to my knowledge the FP script does not lock the bootloader automatically as e.g. the Calyx script does, so downgrading, booting into system and after that isntalling LOS should work out. With LOS you cant lock the bootloader its not support, thus it will stay open. If you want a locked bootloader and avoid the downgrade step, check-out IodeOS or CalyxOS.

This can always happen irrespective of downgrade part

The most important warning is

  • If you install an OS with an older security patch level than your previous OS, Android’s roll-back protection might brick your device when locking the bootloader! Wait until you get a software update with the same or newer security patch level before locking the bootloader.
32

I apologize for the confusion about the fact if the bootloader should be locked or not.

Like multiple people have stated before me: Do not lock it yourself unless you know what you are doing.

My initial note was to indicate I was not sure if the script locked the bootloader again (It seems established now it doesn’t lock the bootloader again) and I could be possible you had to unlock it again before installing LineageOS.

33

Just to clarify this:
no script can lock the bootloader. It can only trigger the process to lock it. But your phone will always ask you to confirm before the bootloader is locked. So if you think (and deny) before tapping an answer you are always on the safe side.

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