[HOW TO] Flash a custom ROM on FP3 with GSI

It works! following your advice i’ve done it with a linux live usb, flash both slots, erase data, and then it finally work :slight_smile: thank you very much !

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I would like to test LOS 16 GIS on Fairphone 3 for daily and stable use. My FP3 arrived almost 2 months ago and still has not been turned on, using the Android stock version is not acceptable for me for privacy reasons.
Reading this post it seems to me that the most stable version is lineage-16.0-20191017-UNOFFICIAL-treble_arm64_bvN.img.xz from sourceforge.net/projects/andyyan-gsi/files/lineage-16.x/
I would like to know if hash files (md5 sums or sha256 or other) are available for these LOS16 GIS versions. No info about on sourceforge.

Sorry, if too off-topic and I know it’s not answering your question. But as you write;;

Are you aware that /e/ OS for FP3 is currently very close to beta testing?


Have you seen the ‘i’ logo in sourceforge? There are sha1 and md5 hashes

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Thank you, I didn’t see /e/! I’ll think about what to install.

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Thank you pigpig for sharing your work and for helping me look better!

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Hello autra - can you explain exactly how you got around this problem? I got the same thing, tried using Format Data in TWRP, (it didn’t work first time but after I did a Repair on data and a Factory Reset I could then do ‘Format Data’). However in fastboot I still can’t do fastboot -w and it won’t boot into Lineage, it just goes back into recovery.

@richplane after the “format data” I rebooted and everything was working. If it goes back into recovery, it means system is not bootable (probably). I’d try to reflash lineage again.

Btw, if you want me to get notified, don’t forget the @ before my pseudo :wink:

I went through the whole process again, got exactly the same results. I wonder if the problem is with the encryption of the userdata partition - when I booted into TWRP the first few times it asked me to unlock the encryption (using the password I set when I booted up the stock OS), but after I flashed the system image (and ran fastboot erase userdata ) it no longer did. Does the FP3 use metadata encryption? That might explain our invalid block sizes wouldn’t it?

Just one short question: Will there be any chance to use a customrom on the FP3 and pass the safetynet-check? (or will it always be that way that -> if custom -> sefetynet-check fail -> some apps won’t work?)

At least it will be the case that even if you somewhen somehow can get this to work, Google can break it at any time again, and most probably will.

If you consider trying this, think about your dependencies on affected Apps beforehand carefully.
This would be in the “Nice to have” category, not in “Reliable solution”.

Hm, I thought that it will be that way. Unfortunantly I am using some apps, which rely on a passed SafetyNet check. So no custom rom for me. But:

I had got LinageOS on my FP3 worked like a charm, but the SafetyNet check ruined it. So I went back to stock.

Keep up the good work.

Hi! Does this means, that ones i got root on my FP3 i can’t unroot that and bring backt to Stock ROM and should Be never able to Update Stock ROM OTA?
Or is it possible to do that?
Thanks towards your answer

For anyone else getting the error along these lines:

Invalid erase-block-size 512: must be a power of 2 and at least 4096.
Invalid logical-block-size 512: must be a power of 2 and at least 4096.
/usr/lib/android-sdk/platform-tools/mke2fs failed with status 1
mke2fs failed: 1
error: Cannot generate image for userdata

I found that this was not a problem with the phone but with the fastboot program - I switched from Ubuntu (18.04) to Windows 10 and I found I could run fastboot -w with no problem. The problem seems to have been that I installed the Android SDK platform tools through apt-get rather than downloading them from developer.android.com. Hope that helps someone.


TL;DR: RTFM :wink: .

To be fair … quoting from /e/'s install instructions

2. Make sure your computer has working adb and fastboot . Setup instructions can be found here.

… where here is a page explicitly telling you to download adb and fastboot directly from Google.

One issue is Linux distributions offering seemingly outdated or otherwise unfit adb and fastboot commands.
Another issue is interested users not following written instructions telling them to “make sure” something works, and how exactly to achieve that if in doubt.

No act of moderation here will fix either issue.
Perhaps /e/'s install instructions could use some bold, signal red lettering in the right place instead.

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Sorry for the noise, post deleted.

This was neither necessary nor my intention. Your post was not noise.

Anyway, I created a topic over at the /e/ forum, let’s see whether something can be done to make it clearer the instructions are really to be followed to avoid trouble.


I’m sorry if there’s a running Lineage thread somewhere, but I couldn’t find the current status of Lineage for FP3.

I saw on the official page that there were a few nightlies for FP2, but is there an active group of people unofficially curating an FP3 version? Or is it more advisable to install /e/ at the moment and customize from there?

I could have sworn there was a thread here but I can’t find it anymore.

EDIT: thanks @Ingo!! I had only searched in Discuss and Help, but forgot about Development. :+1:

The topic about Lineage on the FP3 is right here: [ROM][UNOFFICIAL] LineageOS 16.0 for FP3


In the new firmware (v0120 at the time of writing), there is a vendor.img. Can’t I just flash it on the vendor partition with fastboot instead of reflashing everything?

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