To understand (and document for others): what exactly does this do?
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fastboot flashing unlock_critical will unlock the ability to flash critical partitions like e.g. abl (contains the bootloader) and possibly others. Since the script provided by Fairphone overwrites abl, this command is needed.
After unlocking it will erase your userdata, doesn’t matter if you want to flash back to vanilla anyway, but don’t use it just for fun without backups.
This is mentioned in the docs now, so maybe I just didn’t read it carefully enough (or at all) when they released the .zip 
OT: Can somebody please do something about the formatting of those support articles. Bold text to signify commands ( fastboot flashing unlock_critical) instead of code blocks (fastboot flashing unlock_critical) makes it harder to read than it has to be.
And “Enter 
” instead of Enter, why, just why 
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If you have arrived at a ROM where you feel at home (since this topic is about /e/ let’s assume it’s that 
) and don’t want to flash something new for the foreseeable future, sure, lock it again. That at least keeps you away from partitions that can fundamentally damage your device when messed with (not that disaster can’t be achieved by other means… ).
If your device is working fine and you care about security you might consider relocking the bootloader after that, as the /e/ manual suggests. But beware, if something goes wrong in that process only Fairphone can help you (you’ll have to ship your device to them).
I generally keep everything unlocked, since I know I won’t stop tinkering with my phone anytime soon, but from a security perspective I can’t recommend that!
If you switch back to the stock rom from /e/, Fairphone’s manual lacks this exact command.
Fairphone only writes the command “fastboot flashing lock” under “Locking Bootloader”, but not “fastboot flashing lock_critical”.
That puzzles me.
You are right, fastboot flashing lock_critical isn’t specifically mentioned in the docs.
I can’t tell you if fastboot flashing lock implies lock_critical, meaning if your critical partitions are already unlocked if you unlock your bootloader again, but since fastboot flashing lock completely removes your ability to flash any partitions I’m not sure it really matters.
Somebody would have to try it, but with the inherent risk of bricking in the process, I won’t be that somebody
I did it as follows and it works without problems.
First of all you should run the script from Fairphone.
Then follow the procedure below:
- Boot your device into bootloader if not already there, and plug it to your computer
- Lock critical partitition with the following command
fastboot flashing lock_critical
- Reboot again your device into bootloader, and plug it to your computer
- Lock the device with the following command
fastboot flashing lock
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That doesn’t answer your question if you need to use fastboot flashing lock_critical or if fastboot flashing lock is enough.
But since you have a secure working device now, let’s leave it at that 
To make the process a little bit safer, I’d suggest not only running the script from Fairphone, but actually making sure the system boots afterwards. If you are in the wrong slot and lock your bootloader you will brick your device!
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I have received a reply from Fairphone Support:
Thanks a lot for your patience.
After checking you were indeed right, after using fastboot flashing lock, you must: 1 - Set up the phone 2 - Enable USB debugging once again 3 - Go into fast boot mode and run fastboot flashing lock_critical.
We thank you very much for flagging this to us and we have already advised the relevant team to amend the support article accordinly. 
Kind regards,
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Interesting, so the unlocked state of the critical partitions persists even after the bootloader has been locked.
Wouldn’t it be easier to just use fastboot flashing lock_critical before locking the bootloader with fastboot flashing lock? 
That would get rid of that whole having to set up USB debugging again…
I have asked myself the same question… 
I have also done it so far in the order you have just suggested.
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asking support does not automatically means that every answer is correct.
Often, guys from community has more knowledge then the support guys.
I would never trust them blind…
Why?: should that instruction not be adhered to?
I wasn’t talking about those specific instructions per se, my point was about the amount of commands to execute and the possibility of failure when doing it manually.
While there haven’t been a lot of problems flashing those partitions, as I (wrongly) assumed initially, the amount of bricked phones (not only on /e/) when relocking the bootloader, as suggested in those instructions, is still rather concerning.
So maybe people didn’t mess this up a lot, but those who did (mostly without their own fault) are stuck with a bricked device that has to be repaired (reflashed) by Fairphone
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I try but :
sudo gpasswd -a $bruno adbusers
gpasswd : l’utilisateur adbusers n’existe pas…
Seems that installing /e/ other roms is no longer a one way street…
Thanks for help
Try sudo gpasswd -a bruno adbusers (assuming bruno is your linux username)
Yes ! 
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Hi everyone!
I finally want to install /e/OS on my FP4,
but in the /e/OS-instructions I read:
Caution: Ensure that you flash an image with a security patch level greater than the level of the existing security patch. Failure to do so will prevent you from locking your bootloader.
According to the instruction the /e/OS-image has the security patch: 2022-04-05
My phone has the security patch: 2022-05-05
Does that mean that I need to wait for a new image? (The most recent image seemingly has been created on the 2022-05-26, but no idea if this means that the security patch topic is okay in my case…)
Can somebody advice me on how to proceed?
Hello,
in the ‘IMG-e-1.0-r-20220526188860-stable-FP4.zip’ file, there are three img files: dtb.img, ramdisk.img, ramdisk-recovery.img who are not used to flash the rom. The e/os installation guide do not mention them. Why ? Are they created during building of the files ? Are they necessary or not ? Thanks if you can reply to my question.