OK. Thanks for sharing the information
Did you install the root key?
fastboot flash avb_custom_key
manually and additionally?
Hi guys,
I’m facing a very similar issue, did an installation on my FP4, everything ran smoothly until I tried to lock the bootloader again: after I did it, my phone just started to reboot over and over after 1sec of “Fairphone” screen loading , and there’s nothing I can do to go back to the bootloader, I tried with power and volume down, nothing to do, it keeps rebooting. That’s quite scary and quite upsetting, is there anything I can do to come back to the bootloader? Any idea ?
Thanks in advance.
[EDIT: I somehow managed to reboot with the bootloader by pressing volume down at a very precise timing, and repeated the installation process as indicated by @AlphaElwedritsch , thanks a lot for that. Now I still have fastboot unlocked, which is not great at all, but at least I can use my phone for some time…]
I had the same problem once and will post what I did here even though you already found your way out of the bootloop. But maybe someone else will find this useful:
- Remove any USB-C cable and turn off your Fairphone 4
- If you cannot turn your device off, remove the battery for a few seconds, then put it back in.
- Press and hold the “Volume Down” button.
- Insert a USB-C cable connected to power
- Release the Volume Down button as soon as you see the FAIRPHONE logo
Have you installed the avb custom key as mentioned in the install guide?
fastboot flash avb_custom_key avb_custom_key-FP4.bin
and when yes, could it be installed or did you see any errors?
Means, you have your phone running with iodéOS but still unlocked your bootloader?
That’s not a big problem. And, for the moment until it’s not clear what’s the problem is, I would leave it unlocked.
Yes I did install the avb custom key and it went smoothly, no error to report.
Sure, for now I will leave my phone unlocked, although I don’t really feel comfortable with this status.
The OS is cool and it feels good to be back on Lineage, I’ll wait until we find out more about this scaring issue.
Thank you for your following anyway, it’s much appreciated.
1 Like
Hey guys,
unfortunately I have the same issue as original posted. I just got a new Fairphone4, flashed (successfully) the avb custom key, installed iodéOS (2.4-20220407-FP4), and still… can’t lock the bootloader in the end without ending in a boot loop.
Are you aware that this issue still occurs with 2.4-20220407 and does maybe someone have a possible solution for me?
Cheers
Hello iodè friends,
I had the same problem yesterday with my new FP4 which I could not fix.
Here’s the link to the Fairphone forum:
I tried 20220405 and 20220407.
Thanks to FairphoneHulk, who helps me a lot. All the tip’s didn’t helps to lock the bootloader again, but helps to boot iodè.
Hopefully the system devs will found a solution.
Additionally, I read about some updates which requires to unlock the bootloader again to install.
That will also require wiping all data. For a guy like me it takes a day for reconfiguration.
Is this become very often?
No, wurzelsucher, once the correct avb_key is installed and bootloader is locked, everything is fine.
Updates will then receive via OTA, without wiping data.
Perfect. Hopefully this lock problem will be fixed.
If, I’ll make a special donation. Promised!
but, i think you will get a “better” and faster response if you asked about help and helping hands in the iodé matrix channel: #iodeOS:matrix.org
How can I get this matrix stuff?
Do I need a special app?
you can use element in browser:
or element app via f-droid store:
https://app.element.io/mobile_guide/
After you have create an account and loged in, you can search for iodé room and join
Having the same trouble with my FP4 yesterday, i wondered that there were no statement in this old thread if the problem still exists.
So i just want to inform everybody, that after i have updated my FP4 to actual iode-6.12-20260131-FP4 i could boot the system after i executed fastboot flashing lock_critical but after fastboot flashing lock i got the message Your device is corrupt. It can’t be trusted and will not boot.
So i first executed fastboot flashing unlock and then successfully followed vince31fr‘s recommendation (from 03/2022 - see above).
After that my FP4 has now actual iodeOS with re-locked bootloader and boots perfectly with AVB re-enabled and finally also with re-enabled OEM lock.
As i missed a more verbose / detailed description while re-enabling the bootloader i have logged the commands and their output for others in the same situation.
To keep this thread clean i link my session log to my own webspace and hope this is ok with the forum, You may view or download it from here.
Have fun flashing and using iodeOS on your FP4.
The 20220126 iodeÓS v2.3 build? This is a very old build! In general when you re-lock a bootloader if the version of the current software is older than the prior system, then rollback protection is triggered and it will not boot. So you just need the updated iodéOS build.
Please see the manual install instructions here: ota / ota · GitLab with a link to the builds which should have you find the v7.2 version.
As a note, please make sure you start with NOT the newest FairphoneOS 16 February 2026 build. This will have security patches “one month newer” than the iodéOS builds (as our builds are based on LineageOS which takes a month to incorporate the upstream patches), or else it will again trigger rollback protection.
Also, please make sure that “Allow OEM Unlocking” is enabled before flashing iodéOS. Then if you do trigger rollback protection (or have any other flashing problem causing a “no boot” situation) you can always safely re-unlock the device and try again. But if you don’t “Allow OEM Unlocking” and you lock the bootloader upon install, and the install fails to boot for some reason, you will have a hard brick requiring Fairphone to reset the device.
Good Luck!