Installing /e/ OS on Samsung S9+ - need step by step help

I want to install /e/ OS on a Samsung S9+.

I am quite new to Android phones but I am quite knowledgeable on Linux and I don’t mind tinkering.

I have already read the official documentation and some forum posts regarding the installation /e/ OS on Samsung S9+, but before I start I would like to get some advice from more experienced users to avoid mistakes.

First thing I wanted to ask is: is there any way to make a backup of the phone before starting, or at least a way to bring the device back to factory settings if something goes wrong? If yes, how?

Regarding the mode compatibility, the good news is that it is a SM-G965-F, so it should be officially supported by /e/ OS.

The bad news is that it runs on Android 10, Baseband version G965FXXU8DTC5 and according to several forum threads, such as this recent one, this particular version does not allow downgrading to Android 9, and thus installing the /e/ OS version for this device.

This is the thing I am most confused about. Is it really the case? What does “not allow” mean in this case? Does it mean that I will brick the phone? Or will it just refuse to install? On the other hand, my understanding is that Lineage OS 17.1 supports Samsung S9+ with Android 10, with latest firmware. So should I be still able to install Lineage OS until /e/ OS is officially supported on my device?

Well maybe I will stop my questions for now until this is solved, as I won’t waste your time asking for guidance on how to install /e/ OS if my phone is not supported.

Thanks a lot for your kind help and thanks for this amazing project!

1 Like

@archje ‘cobra übernehmen sie’ :slight_smile:

Seems your help is needed

First, download the stock ROM (the one you are currently on) for your device. This way, you will be able to restore the phone very easily with Odin (needs Windows).

I don’t know a way to fully backup before doing anything. But once TWRP is installed, you can proceed to a full backup (system + data) (but not the internal starage, which is what you can access in the Files app or by plugging the phone to a laptop).

Yes you are able to install LineageOS 10.

You may need to take a look at this howto, in case you have a confirmation and can proceed to a downgrade to install /e/, or to install LineageOS :

Great, will do.

Actually I don’t need to backup the phone, it was my poor choice of words, it is new there is no data there, I just want to be able to factory reset it at any time. Is that possible? Do I need for that with the stock ROM I have to download somewhere? Does installing custom ROMs somehow “void the garanty”?

Yes, that’s also my understanding. But ideally I want /e/ OS! I should have ordered directly a pre-installed phone at /e/ OS, but too late…

I also read this guide but I fear it is a bit outdated… As the Android versions are not the same. My understanding is that since january or february 2020 some new security updates on this Samsung phone forbids to downgrade to Android 9 (and /e/ OS is built on Android 9, right?). HOW does it “forbid” and what does “forbid” meand (bricking the phone? just refusing to install?) is what I haven’t yet understood…

To restore, follow the HOWTO I mentionned above but instead of clicking on “AP” in Odin and select the TWRP file, select the the stock ROM file you have downloaded and unzipped. And leave the “Auto-reboot” box checked.

To install the bootloader you need to unlock the bootloader, and this could void the warranty.

It’s not outdated at all, I updated it recently.

@harvey186, these words are unforgotten: “Wir wissen, dass Ihre Chance gleich null ist. Sollten Sie, oder einer Ihrer Mitarbeiter während des Auftrags gefasst oder getötet werden, müssen wir leugnen, Sie zu kennen. Dieses Band wird sich in wenigen Sekunden selbsttätig vernichten! Kobra, übernehmen Sie!”

1 Like

Hello @pitorel, from your research you’ve come to the right conclusion: A downgrade from StockROM Android 10 #G965FXXU8DTC5 to StockROM Android 9 is no longer possible due to Samsung’s security guidelines for updates. In fact, you can no longer downgrade to StockROM Android 10 February or January 2020.

This red framed note hasn’t been displayed for at least half a year. Samsung simply dropped it under the table. But the consequences have remained.

If you don’t believe it, try a downgrade. Nothing will happen to your S9+. The initiated flash process is simply cancelled and you will receive an error message in red on the S9+ display, which goes something like this:

Odin Mode
Download Speed: Fast
Poduct Name: SM-G965F
Current Binary; Samsung Official 
System Status: Official
FAP Lock: Off
Secure Download : Enabled
Warranty Void ....
RP Swrev:: ...
SW Rev. "Check Fail (bootloader) Device ...

When /e/ OS 8.1.0 Oero /e/ for star2lte dev (oreo) flashes on the Android 10 bootloader, this will result in the known boot loop under /e/ OS.

In this context, the warning notice on the /e/ dokumentaion says

Warning : Downgrading smartphones already running on Android Q […] to Oreo or Nougat can lead to instability or in worst case block some devices

Thanks @archje for your detailed answer.

Well, this sucks. I don’t quite understand how this is enforced on the device if this happens at the software level? How does a simple OS update make it impossible to downgrade the device? To me, it’s like saying "this particular Windows version on your computer makes it impossible to boot into another operating system such as Linux at the hardware level".

“Nothing will happen” -> you mean I would be able to factory reset it to its current state? It won’t “brick” the device? I don’t mind trying but I obviously don’t want to destroy my phone.

And also: do I need to download a stock ROM to factory reset this phone if the /e/ OS installation fails?

@pitorel, the device manufacturers have the possibility to lock the bootloader completely on firmware level. For example, the carrier US Verizon is notorious for blocking the bootloader for G°°gle Pixel and Samsung devices for life. Huawei stopped its Bootloader Unlock program some time ago.

From this point of view, Samsung is still “gracious” with its current devices. But with Android 10 and 11, Samsung is tightening the thumbscrews.


You can always reflash the StockROM Android 10 #G965FXXU8DTC5, for example with Odin3.

This can also be useful if you want to uninstall or remove a custom recovery like TWRP Recovery.

So a simple software update effectively locked the bootloader firmware to arbitrarily forbid installing Android 9 on the device, right? Wow, that’s really evil. If the phone would have stayed just a couple of updates behind, that would not be the case, correct?

That’s so frustrating I am really really angry. Coming from the Linux word I have a very difficult time accepting this reality, that a software update locks the device into a specific OS version… I thought Android phones were different in that regard from iPhones, but I guess not that much, or it just depends on the manufacturing company… Sorry for all the newbie questions, but the Android ecosystem is completely new to me and there are a lot of different concepts I am trying to grasp.

So the conclusion is that the best I could do is to install LOS 17.1 in the meantime until an /e/ OS Android 10 version is available for my phone (if ever?), right?

  • … nstalling Android 9 on the device, right?*.Right!

  • … that would not be the case, correct? Correct!

  • … is available for my phone (if ever?), right? .`Right! but …
    If /e/ OS 9-pie is available for the S9+, OS switching will probably be possible. I’ve been able to try it so far. However, /e/ OS 9-Pie is such a rough-looking OS that I’m hopeful.


Until stockROM Android 6 Marshmallow, Samsung had not blocked the bootloader. Now get really angry. I don’t know but I suspect that G°°gle is also behind it.

G°°gle is already making it harder than before for the developers of custom ROMs based on ASOP 10. Android R (11) will again cause problems and will move further and further away from “open source”. G°°gle determines what will become of Android in the future. All others will have to participate or build a complete new operating system à la Huawei OS.

Do you think flashing a previous firmware version for this phone to revert this firmware update could work (found on sammobile)? Is it dangerous?

Which firmware version do you intend to flash?

I can’t even get to OEM unlock the device… The option does not exist in the developer options menu. I tried all kind of solutions found online, nothing worked. Maybe they removed this option also with their latest firmware update. So I cannot even install the latest Lineage OS version for this phone, which should work with Android 10.

Well, thank you Samsung. I will never buy a Samsung device again. 400 euros thrown away…

This one: G965FOXM7DTAA (30.01.2020)

Found here:

Together we can try to install e.g. LineageOS 17.1 on your S9+ - if you want to.

We just have to proceed step by step and with caution.

Think it over again in all peace and quiet. Tomorrow is another day …

That would be great :slight_smile:

I am following the instructions here but I am unable to OEM unlock the bootloader, so that may be a new blocker introduced by Samsung. I already did the “fake date and time+disable auto updates” trick that many online forums offered as a solution to enable the OEM unlock option, but it didn’t work.

But first do you think it is possible to revert the phone to a previous official firmware update as mentioned above? Maybe that way I could install /e/ OS?

I wish I had just bought a phone with preinstalled /e/ OS on it, but I thought I would be smarter by installing it myself. Should have known better.

Anyway this experience may be useful for further reference and troubleshooting to people with a similar device and problems…

Okay, let’s start at the beginning.

Is AUT Switzerland your preferred region?

Yes.
My current build is G965FXXU8DTC5 and in the “Software Information” under “Service provider SW ver.” that it has AUT written multiple times.
I don’t know what “AUT” refers to by the way.

Well, I ask to make sure that I’ve understood everything correctly and can give you the right tips.


It’s Samsung’s will that you cannot downgrade to this firmware version G965FOXM7DTAA (30.01.2020).

It is only possible to upgrade to the current version G965FXXS9DTD7 with April 2020 Security Update.

It is also possible to flash the existing firmware G965FXXU8DTC5 again with Odin3.

Your host machine works with Wind!°ws, doesn’t it?

Absurd and against everything I stand for, but I guess there’s nothing to be done about it.

Should I do that? Or no benefit?

Meaning if something goes wrong I can reset it to factory settings (i.e. as it is now) and hopefully resell it? :slight_smile:

No, I run Linux, but if I REALLY need Windows I could boot a Windows 10 disk that is laying around…