/e/OS S to Fairphone4 (on StockRom Android11)

I have opened this thread because my information and questions are out of place in this thread.

The conversation regarding the problem Fairphone4 users face with a new device with StockRom (Android11) should be continued here.

I wrote an eMail to helpdesk@e.email after advice from @manoj, in which I described my problems and thoughts before the installation. As soon as I have a solution and a successful installation on my Fairphone4, I will comment here.

Of course, all opinions and questions about the topic are welcome.

You can install /e/OS 1.5-.1-s (Android 12) over stock Android 11 Fairphone OS, it shouldn’t be a problem. (all data will be wiped)

Don’t know about downgrading back from /e/ (Android 12) to Fairphone OS (Android 11), but it seems the revert back flashing procedure will wipe and format all partitions, so should be ok as well…

See details here:

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Interesting, are you quite sure that your approach works against the warnings in the installation instructions?

Thanks first, but I’m still waiting for an answer from helpdesk@e.email

I want to be absolutely sure with the installation, as I don’t want to have an expensive paperweight :wink:

I have another question regarding the OEM Unock in the developer settings.
After successful installation and relock of the bootloader should the OEM unlock setting be locked again? I found no information about this in the installation instructions. Or does OEM Unlock remain enabled?
How did the Fairphone4 users handle this with their reinstallation?

Not against as stock android 12 don’t exist

Caution: Do not install /e/OS on top of a higher version of stock OS. Before installing /e/OS ensure your device has the latest stock OS of the same version as /e/OS. If only lower versions of the stock are available then install the last available lower version before installing /e/OS.

Understand it as : check that you have latest available (but not higher than the one on witch /e/OS is based) stock firmware installed

e-0.18-r based on android 11 run very well on my device on top of android 4.2 based stock firmware

Unfortunately, I have not yet received any feedback from helpdesk@e.email. Therefore I decided to venture the installation at my own risk.

I have installed on a new Fairphone4 (Android11 security patch March 2022) the /e/OS version IMG-e-1.5.1-s-20221102231514-stable-FP4.zip with security patch 2022-05-08.

I could relock the bootloader without problems.

The installation went smoothly, the Fairphone4 breathes /e/OS air from today and feels comfortable.

Can I disable the OEM unlock in Developer Options again? That is the only thing that is not described from the installation description. Or does OEM Unlock remain enabled from the time of installation?

Again, many thanks to the DEV team and all involved for the good work and effort with the implementation of /e/OS.

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OEM unlock is not used in /e/OS, so can not be locked again.

OEM means “original equipment manufacturer” that is activated by default on the stock ROM.

This is an additional lock from the device manufacturer. To unlock this security you need to ask the manufacturer (in this case Fairphone) for a unique code that permanently releases the device so that you can install a custom ROM instead.

Thus, the manufacturer knows that this device has been released from the original operating system.

/e/OS not being the manufacturer of the device, can in no way reactivate this lock.

I hope you will enjoy your Fairphone 4 on /e/OS as much as I do :wink:


Please share a screenshot of your “settings -->about the phone–>android version”


Thank you for your detailed explanation. However, I still have a question. When unlocking the OEM lock, you had to generate a key from the Fairphone manufacturer’s site.

The key is made up of the IMEI and the device serial number. I have the key. But it is only used for unlocking, not for relocking?


My request was bad formulated, what i want to check is the security-patch date,
Please clic on android version…


Just now helpdesk@e.email confirmed that an installation of a Fairphone (Stockrom Android11) with /e/OS (S - Android12) is possible.

It should be noted that the security patch of the /e/OS installation is newer than the one on the smartphone (StockRom Android 11).

Thanks to all who helped me. I really like my new phone and /e/OS runs fabulously.


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The OEM unlock is to allow you to unlock the bootloader the first time from the original stock ROM, after this you can unlock and relock the bootloader when you want, as its been released from the manufacturers “lock” with OEM unlock.

As @stanwood said its an additional lock that you only have to unlock the first time.


Thank you @GreyLinux

i’m just careful when i don’t know 100% about something. For this reason I ask specifically again, so that I do not break something out of carelessness. Experienced users and developers simply have a better insight.

I have now locked OEM again. After that, a restart is due, which I have executed. The Fairphone starts without problems and I am very happy with it.

Thanks again for the expert support here in the community.

Stay healthy everybody


I completely understand, I’m the same, I was unsure myself about installing an android 12 custom ROM over an android 11 stock ROM especially with the pending fear of anti rollback issues and security patches , etc. Its why a forum is brilliant for friendly advice. Glad you got it all installed and sorted.


FWIW: Are you sure that you “locked OEM” (in developer options)? Sounds rather that you “(re-)locked the bootloader” (using fastboot). This causes a factory reset and reboot of the phone.

I switched from on to off.

Ok, then you were right.
So what’s the advantage of doing this? Doesn’t it just bring some risk with it (if something breaks and system does not start you won’t be able to unlock the bootloader again so it might hard brick your device…)?

To be honest, I hadn’t even thought that far ahead. My intention was to protect my device against manipulation. The OEM lock is active when the smartphone is delivered. That’s why I thought that as soon as /e/OS was installed, I would activate all the protective mechanisms again.
Is this a mistake?

Well, difficult to say. I described he risk coming with it above.
Advantage? Well, what I read so far could be that it would be hard for someone stealing your device to clean and sell it. But I’m not sure about that.
Maybe others might find any reason for reactivating OEM unlock…

I’d be interested in that, too. All opinions are welcome.