Understanding the basics of installing /e/OS on FP4

/e/OS Devices Fairphone
1

Hi,

I want to install /e/OS on my Fairphone 4. As I’ve understood the Security Patch Level of the OS I’m installing should be more recent than that currently on the phone. My current SPL is March 2025, and so I should be ok if i select the most recent version of /e/OS 3.0.1 with SPL June 2025 right? (IMG-e-3.0.1-a14-20250607498722-official-FP4.zip)

But, if for some reason and heaven forbid, I need to go back to stock OS which is Google Android 13 for the FP4, will I risk not being able to re-lock the bootloader coming from /e/OS Android 14? Or is the Android version number not critical in this respect?

2

Hello @OttiSral,Welcome to the /e/ forum.

going back to FairphoneOS and doing this, downgrade Android base version is still possible…

3

Is it June or May? [1]

Downgrade of Android version is irrelevant.

If Android SPL has been locked into phone in FairphoneOS or /e/OS by locking bootloader then this value in the Index cannot be rolled back.

If you are only testing /e/OS you might consider not to lock /e/OS then you can go back without worries.

I would suggest you write down or grab a screenshot of Settings > About phone > Android version > Android SPL (also Vendor SPL but not related to the locking issue) on any locked system on the phone before you make changes.

Fact check
Source: Releases · e / os / 🚀 Releases · GitLab

This /e/OS 3.0 version includes the Android security patches available as of May 2025.

Source: Install /e/OS on a Fairphone FP4 - “FP4”
FP4-dl

Existing: March 2025
Proposed: May 2025
Is ok.

4

Thank you @piero and @aibd , that is very good to know.

I agree the Install /e/OS on a Fairphone FP4 - “FP4” page does say May 2025, but on the linked page /e/OS build downloads the latest is June 7’th and the second latest is 21’st March. Perhaps the instructions page should be updated or rather not mention SPL dates at all?

I did consider not locking after installing /e/OS, but my testing involves banking apps, so I expect to have to, right?

5

But surely you are looking at / quoting “build dates” ???

This subject is highly specific to Android SPL only.

6

@aibd , right you are. I assumed this important information was part of the filename for each build.

Two more questions;
Will the web installer allow to lock the bootloader or is the manual approach needed for that?

What is the significance of “Vendor SPL”? Is it “Google Play system update” under Settings > About phone > Android version? (Quotation marks as it is a translation, it’s the one below Android SPL).

7

From what others have reported it seems the web installer stops short of locking the bootloader leaving the user to do it as a separate manual job.

I guess you are translating this from FairphoneOS. The range of Android updates are described here What’s new in Android's May 2025 Google System Updates. That date relates to installed Google Play Services.

Do you not see an entry more close to “Vendor security patch level”?

It would be interesting if Fairphone do not quote Vendor SPL on their phones in light of the term not appearing in their release notes

and this question is asked Vendor Security Patch Level (SPL) in Fairphone 5 today.

8

This is what I’m seeing;

Screenshot_20250629-211041~3
Screenshot_20250629-211041~31080×2340 115 KB

Ok, thanks. To check e.g. banking apps, the bootloader typically will need to be locked no?

9

It depends on the banking app. Some don’t check anything. Some check for unlocked bootloader, rooting, or Android version, or any combination of those things. I would try the app and see if it complains before doing anything else.

There are a few banking apps won’t allow any non-OEM version of Android so you could run into that right off and there’s nothing you can do about it. Well at least I’ve not heard of anyone spoofing the Android version to get past that.