Stuck in fastboot mode

Thanks. I prepare myself to follow the idea of Tux17 in case of. And then try later to install /e/ on my FP4.

Maybe @ff2u will have a better idea :slight_smile:

Last question : is it not a problem to let bootloader unlocked after reinstall /e/ ?

It is if someone malicious take your device in his hands.
Most supported devices can’t be relocked, only a few can.


Actually you didn’t do a mistake but it’s unfortunately a problem of the “anti rollback feature” implemented. You very probably had FPOS installed before with a newer security status date than /e/OS now. So this leads to the “phone corrupt” message on relocking the bootloader (and so activating anti rollback feature).
I hope that “OEM unlock” is still “enabled” (this should be the case with installing /e/OS). So did you try to go to fastboot mode and type fastboot flashing unlock there?

This will probably not work (to reinstall the OS) as this is not possible while bootloader is locked… (and btw I would not reinstall FPOS - as this will switch OEM lock to “disabled” and make it even more difficult…)

If you’re interested in all details then you might read the (lengthly) topic here:


To be a bit more detailed:

Yes, locking bootloader may help in this case. Your data is probably not directly in danger in this case (as data is encrypted). But someone could flash you malicious code (and so do anything with your device once you keep using it with a malicious OS.

FP4 supports it. But only if you flash an OS with a newer security status date than the OS installed before.

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Thanks a lot @ff2u ! My actions seem more clear now.

I try and I have now “DEVICE STATE - unlocked” on my fastboot mode. Is it a good news to find a solution ?
Is there a solution in the lengthily (indeed !) topic ?

That’s very good news.
Now you are at the point you were before locking the bootloader.
So your device should boot.

It depends. For some there was only the solution to send the device in (if OEM unlock was disabled and so the device was hard bricked). For others the solution was to unlock the device again and use it unlocked…

If you really want to have the bootloader locked, then you have to wait until the next /e/OS update. Then you’ll probably be able to successfully lock the bootloader. BUT this locking will do a “factory reset”. So you need a good backup then or have to setup all from scratch.
Before locking the bootloader please always check OEM unlock status! I’d never lock it if OEM unlock is disabled as this could lead to a bricked device. You can check OEM unlock status in developer options or via fastboot (fastboot flashing get_unlock_ability results in “1” for “OEM unlock” status “enabled”).


IMHO this message is a “warning” but no “error”. You’ll only see it when booting (what probably won’t happen too often) and you may get used to it. Still, as mentioned above, you’ve to decide for yourself if an unlocked bootloader is ok for you or not.

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For example, With locked bootloader, you can update /e/, but not upgrade.

At least an upgrade will for sure be possible with an unlocked bootloader. For some devices an OTA upgrade to a new major OS release is available or under development, so it might be possible for the FP4, too…

Oh I’m hapy to read that !
But I’m still stuck in the fastboot mode. No matter my choice between “Start/Restart Bootloader/Recovery mode/ Power off”, I always come back on that fastboot mode page.

Or maybe, if I understand correctly, I can relaunch the easy-installer because it’s unlock ?

Do you mean send it to FP and cost me 30€ ?

I tried and I got a “1”. Still goof news.
I understand the need to be at the same “level of update” before locking the bootloader. Is there a page on the forum or something else where I can be sure in the future ?

I read that unlock bootloader block some application, like banking. Is it right ? As a newbie, it’s hard to estimate the risk beyond this (like hacking).

Thanks again to all for answering all my questions ! This is really kind.

I find this subject on FP forum : Fairphone 4 "locked in fastboot mode" - #7 by hirnsushi - Fairphone 4 - Fairphone Community Forum

So I switch the slot thing from “a” to “b”, but I have no idea of the impact and what it did inside of my phone (if you can explain to me please).

But at least, I can go outside of the fastboot mode and now I have this on my screen, and no idea what to do (and I want to avoid to do something wrong).

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I follow the guide from Piero and I used adb sideload but I got this message on my phone.

I downloading the zip from here and I choose “stable” version as it may be installed the first time with easy-installer.

What should I do ?

Installing via ADB sideload doesn’t work with the FP4 install files currently available on the download pages. Those files get installed in fastboot (aka bootloader) mode following the official install instructions.

I don’t know where current OTA stable files possibly installable via ADB sideload come from, but links to older OTA files (up to 1.5-r-stable) are visible in (lines starting with “url:”).


Yes, you might try this.

Currently not necessary. The price seems always to be a matter of discussion…


I think that’s no longer the case.

I suppose you already know in the meantime that this is recovery mode where you have other options to recover your system…

As mentioned above this probably happened as you didn’t use the zip file which can be sideloaded via recovery…

I’d recommend to use fastboot mode and try to reinstall the system from there (as mentioned in the official install instructions linke above).

If you don’t succeed you might try to contact a Fairphone angel and ask for local help. There is AFAIK one around Paris:


(édited because there were error in typo) :

are there expected to be diferent files ?

They are different in that they are dev and stable.
But both are not OTA files, both get installed with fastboot. Just download them, have a look inside and have a look at the official install instructions … it’s a match :wink: .

Download (link from for comparison and have a look inside … OTA file (and filename doesn’t start with “IMG”, but that’s cosmetics).

Oh, I just put this link together on a whim, and it’s valid … … OTA file.
(I just took the given 1.5-r OTA link and substituted in the 1.6-s-20221129238946 part from the IMG download files.)

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So, @LG75 can try to use this within the recovery-e ?

I installed FP3 OTA files with ADB sideload on my Fairphone 3 successfully, but I don’t have a Fairphone 4 to confirm it would work the same way.

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It looks like it could be the way used by the ”easy-installer", isn’t it ?

I get outside of recovery mode because all manipulations were too complicated for me.
I follow your instructions, using officials instructions, and it finally works !!

I can now have fun with my FP4. And I guess I won’t try to lock the bootloader :grin:

I hope i will be easier with all updates in the future. Thanks everyone !