Error when trying to re-install FP4 Stock Os

Receiving the following error code when running “flash_fp4_factory,command” to reinstall FP4 OS. Why am I receiving this error, and how do I get around it? All I have done so far is unlock USB debugging (Phone already unlocked) and run the flash_fp4_factory.command.

INFO: flashing partitions…
Sending ‘abl_a’ (148 KB) OKAY [ 0.006s]
Writing ‘abl_a’ FAILED (remote: 'Flashing is not allowed for Critical Partitions
fastboot: error: Command failed

ERROR: Could not flash the abl_a partition on device cf6d1af5.

1 Like

Follow the steps to “Unlock your bootloader”. If you did so, you probably missed step 7.

Please be careful and do not lock your bootloader afterwards without double-checking get_unlock_ability!


Hello, thanks for your reponse. Unfortunately, my bootloader is already unlocked, and USB debugging and OEM unlocking are already on. I didn’t lock the bootloader after installing a custom ROM.

If it were the case it would be far too easy

so you did also unlock_critical? You had Iode, correct? Not sure if critical is unlocked to flash Iode and if yes if you relocked it?

Edit: what I read here unlocking critical is not part of the Iode instructions…


Yeah, @yvmuell is right, according to their website they explicitly don’t want you to unlock critical:

Unlock your phone by following the instructions from Fairphone website, but do not unlock critical partitions (do not execute ‘fastboot flashing unlock_critical’).

Since you want to install stock FPOS now, you should follow the official instructions linked above, and that includes fastboot flashing unlock_critical.


This Worked! Thanks so much for all of your help. Max was correct from the beginning.


Am I now able to relock the critical partitions separately from the entire bootloader to reinstall the iode OS?

I have read some guides saying there is a bug and after reinstalling FPOS you cannot relock the bootloader or it will brick the device. Is this still correct?

You might relock the critical partitions (it won’t brick the device, this may only happen by locking the bootloader in case you’ve now installed an older security patch level than before and OEM unlock is disabled) but in case get_unlock_ability is 0 (OEM unlock is disabled) you won’t be able to unlock critical partitions again until you do OEM unlock. But this will probably be greyed out in developer options until you lock the bootloader.
So in that case relocking critical partitions would still be risky.

I haven’t relocked them and installed iodé OS without any problems. Do you want to relock your bootloader with iodé?

My phone has get_unlock_ability set to 0 and OEM unlocking is disabled. But in iodé OS, the option isn’t read-only (it was when I flashed stock again before). So it should probably be okay.

Nevertheless, I didn’t even risk touching the OEM unlocking switch and will propably keep my bootloader unlocked until the problem is solved and locking with the stock ROM works flawless. Then I will reflash stock once, lock critical and return to my custom ROM of favor. So in case of problems, I have the stock ROM installed.

TL;DR: I’m a chicken. :smiley:


Hi Max,

Strange as all the iode OS install guides warn not to unlock critical partitions. When I unlocked the critical partitions, I saw iode booted into a recovery screen before I flashed with the stock ROM.

I am not planning on locking the bootloader at the moment but would like the option with iode in the future.

So there is no way to lock the critical partition now without bricking the fairphone? Even if I lock the bootloader with stock ROM and then unlock on stock ROM?

Def dont lock the bootloader neither with FPOS when geht unlock ability is 0!

I think I remeber that Iode does not mention the critical partitions as they suspected that might be related to the bricking issues. I think no one here can give you any 100% guarantee for anything


Where did you find this information. It’s imho not true as locking critical partitions does not brick FP…

Even more when iodéOS is installed, if

is always true. If this is not greyed out in your case just enable OEM unlocking and you’ll be safe.

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