Fairphone 4 /e/os lock bootloader

Help Fairphone 4
1

I just installed /e/OS using the /e/OS Installer from Web Browser. The installer wanted me to lock bootloader, but I declined because fearing of bricking.

/e/OS booted fine

fastboot flashing get_unlock_ability

returns

(bootloader) get_unlock_ability: 0
OKAY [  0.001s]
Finished. Total time: 0.001s

My phone history is Fairphone 4 is Android 11. I unlocked bootloader and installed Ubuntu Touch. Latest update was Ubuntu Touch is 20.04 OTA-9.

/e/OS is now freshly installed. Is there anything I can do to allow locking the bootloader? Will I be able to if I wait for /e/OS next security patch?

From what I understand I need to see 1 in order to lock?

I’m also wondering if they’re would be any difference in locking with /e/OS installed or locking after freshly install /e/OS through the installer.

After installation I couldn’t check unlock_ability in fastboot. I had to boot /e/OS and boot back into fastboot.

3

Documentation on safely locking bootloader for Fairphone 4 with /e/os is very poor, but I think I may have found an extra detail worth noting.

Step 1 - To install /e/OS on a Fairphone 4, the security patch level of the /e/OS build must be equal to or newer than the security patch level currently or previously installed on the device.

My device was Ubuntu Touch is OTA-9, released on June 3, 2025, before that Android was installed over 2 years ago.

New OS is /e/OS version 3.0.4, released on July 11, 2025

Step 2 - I used /e/os web installer which then asked to lock phone. I declined and booted into /e/os to confirm locking the phone.

I ran command

fastboot flashing get_unlock_ability

and received

(bootloader) get_unlock_ability: 0

Indicating that I can’t lock the bootloader, but this is because of a missing step not outlined in most forums.

Step 3 - Developer Mode/ OEM unlocking

This is the missing step not clearly outlined. While in /e/os go to /setting/about phone/build number and click 7 times.

Now go /system/developer options and toggle OEM unlocking on

Now boot into fastboot

run command

fastboot flashing get_unlock_ability

and receive

(bootloader) get_unlock_ability: 1

I re-conformed by disabling OEM unlocking which again switched my result of 1 back to 0. Point is that OEM unlocking must be toggled on to receive a 1 for locking the bootloader

Probably would have worked during /e/os installer, but I had no way to confirm in fastboot.

The only other thing is to confirm your /e/os version is official.

Lastly I saw on another form a user saying not even (bootloader) get_unlock_ability: 1 guarantees you won’t brick your phone.

So my question would be am I now safe to lock my bootloader with /e/os official with (bootloader) get_unlock_ability: 1?

4

@dp27thelight I’m very interested in this too. I want to install LineageOs again, install gapps and then lock the bootloader. Locking the bootloader improves compliance with banking‑app security requirements like revolut. I hope.

5

You cannot lock the bootloader when LOS is installed…

1 Like
6

You’ll need /e/os. I think that’s the only fork of LineagOS that supports a locked bootloader.

7

all LOS based custom ROM support to lock the bootloader, the only 1 that does not is LOS

8

That’s good to know thank you. Do you know the answer to my question on the original post?

Question in relation to Fairphone 4. I gave my phone history on the original post.

9

As far as I know, if you really do have the official (!) build for /e/OS for your phone, and the SPL is the most recent (last month’s SPL. Check SPL level, not release date. It’s on the OS image info), and get the right response to get_unlock_ability, you can get to locking.
Be aware that it’s going to erase everything on the phone to go back to factory.

10

Unfortunately OEM unlocking is now greyed out in system settings.

Not I can’t get it back to (bootloader) get_unlock_ability: 1

Documentation is really bad on locking bootloader.

I feel I could probably fix by just reinstalling with the online installer.

Now that I know I need to enable OEM unlocking. I’ll install a fresh copy enable OEM unlocking like before

Check

(bootloader) get_unlock_ability: 1

Then lock.

11

Well you did say that you declined locking when you installed /e/OS…
If you installed official build, it may be the same feature that deactivates OEM unlocking.

The fix is indeed to reinstall from scratch.
The automated installer should lock it from the installation script. You just have to confirm physically.

12

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