Hello @piero ,
I am not sure to understand your answer. I understood how to get the security patch from my phone, and I have some idea about the security patch date of the /e/OS release (even if it not clearly stated).
My question was about what stock ROM to flash (following @jamesaepp advises) as this may lead me to have a newer stock ROM (7th july) than /e/OS build (1st june). He told me to flash the newest possible ROM… but I don’t understand then how to flash /e/OS as I should have /e/OS build newer than stock ROM.
It is confusing. This is the best summary I can give:
- Downgrading the operating system (17 > 16 >15) is safe*.
- Downgrading the bootloader is safe*.
- Upgrading the operating system (to any build, major or minor) may upgrade the bootloader.
- Downgrading the bootloader prior to May 2025 is prohibited (or can lead to device bricking if you aren’t careful).
- I think there’s logic during the flash process to prevent downgrades that won’t work but I’m not brave enough to test it.
*see point 4
Unfortunately this comes down to a bit of “YMMV” so without looking closely at the exact path you’re taking, I can’t say for certain you are going to be safe, but I think the advice from the others in here is correct that as long as you stay on the latest official build/release, it should include a bootloader that won’t risk a brick.
Hope that helped.
Great explanations, thanks again for your patience 
So I am thinking to flash twice the latest A17 stock ROM for Pixel 8.
Then I’ll flash /e/OS, either /e/OS official A15 or /e/OS community A16.
I understand from your last message that I don’t need to have the ROM to be flashed with a more recent bootloader than the ROM on the device, as long as I am far after May 2025 bootloader (what is my case anyway).
You need a build that include “android security update” newer than march 2026
Installing current a17 based GoogleOS look risky to me.
[HOWTO] a Safe Guide to install "IMG-e-builds" even if the /e/ web installer fails
Where are you pulling this “need” from/what do you mean by “need”?
My memories are close to/over a month old now but I had no issue downgrading from the (latest) official/Google A16 build to the (latest) official/Google A15 build.
We’re talking about avoiding bricking, right? Which is solely a problem of the bootloader, right?
That is my understanding, but consider the source - I am just a user like you. 
@jamesaepp This is newer security patch than e-4.1.1 that is 2026-07-01
So what? Is there something that prevents downgrading a newer ROM version to an older version (or entirely different ROM provider for that matter)? What is that mechanism?
Consider my post here: Pixel 8 (shiba) - Installation Support (May 2025 bootloader anti-rollback) - #8 by jamesaepp
Between steps 4 and 5 I went from CP1A.260305.018 (A16, March 2026) all the way back to BP1A.250505.005 (A15, May 2025) without issue.
Is there something “unique” to official/factory Google images that don’t extend to custom operating systems like /e/?
@jamesaepp your last post contains 4 question marks. I have a great deal of sympathy for @croulibri, he has a number of options but only needs answers.
Forgive my bluntness but I have to say that sideload a17 to both slots of a device already on “safe zone” a16 with an SPL ahead of any /e/ ROM is not a thing I would advise someone else to do.
@croulibri I will avoid reinterpreting the original Google advice but you can read there about the suggestion to “sideload both slots”. It was given for very specific reasons to “experimenters” in danger of getting “the wrong side of the line” which was set in May 2025. Maybe there is a judgement to make, but if your device took a natural path of updates from May 2025 to May 2026 then both slots are already “safe”. In Android “Never go back” is designed in so it is best avoided without reliable advice.
Your Post #22 showed a good understanding of the situation and I believe the fundamentals were answered.
I suggest your next step would be whether your preferred path is
- a15 official or
- a16 community.
Good luck
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Thanks all for your time and explanation
To avoid any risk, I am thinking to flash twice the last Google Stock Android A16 (16.0.0 (CP1A.260505.005, mai 2026)
Then to flash the last /e/OS community A16 (IMG-e-4.1.1-a16-20260718651040-community-shiba.zip)
Like that, I understand I take limited risk by having a new Google stock ROM flashed properly twice + using a /e/OS ROM newer than the Google stock ROM
Should be fine and then happy with /e/OS 
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I find it shocking no one can actually explain the “why” of how my advice is harmful/wrong/whatever.
It may be unnecessary in the user’s situation, but I don’t see how it’s a problem.
Maybe someone should update the friggin documentation with source material…
This kind of crap attitude and documentation is why I left LineageOS in the first place and is why I am on Graphene.
Indeed, I agree. This is from July 2025
(My added emphasis of my words.) Here Google used the words
“a bootloader update that increments the anti-roll back version for the bootloader.”
The wording during May 2025 is not recorded … but it sure was unhelpful to ordinary readers.
Android does contain switches that manufactures can choose to apply or ignore. Personal opinion, I believe that as these are consumer devices with guarantee and all, Google Pixel would choose to deploy this killer fuse in a way that should be unnoticed by ordinary consumers.
However that was in the past, and never mind my hypothetical book reading; thank you for your documented description of what can be done in Post #23.
Except it may not be true, and we shouldn’t be thankful of people spreading potentially false information. That’s what gets us all into this mess of misunderstanding.
I’m short on time and can’t give a detailed response right now, but what I’m finding is there’s a “system” of locks here that we need to be cautious around and it’s hard to be perfectly clear every time we reply or write documentation:
- Bootloader anti-version-rollback (prohibits booting from older bootloaders)
- I’m not sure if there’s a safety mechanism in fastboot (and OTA updates) to prevent accidental installation of old bootloaders
- Security Patch Level.
- Some comments in this thread claim SPL prevents installing any ROM (Google/factory official or not) not meeting the SPL value ?burned? into the flash after a successful update.
- Bootloader locking
- Here I think is a big source of miscommunication. I don’t think SPL matters if bootloader is unlocked. Obviously an unlocked bootloader has big security implications.
- Bootloader “unlockable” (I forget the term)
- In addition to whether the bootloader is currently locked or not is the ability to unlock the bootloader, which I believe requires a fully bootable and verified OS in order to flip that switch, so that alone hugely complicates the system.
Throwing out another point of miscommunication source:
“Brick”
What one person considers a “brick” may not be considered a “brick” to someone else.
Is a device “bricked” if it can boot to an unlocked bootloader?
Is a device “bricked” if it can boot to Google’s factory image/OTA but it’s SPL is so far ahead of a community ROM that that ROM can’t be flashed and with a bootloader set to locked mode?
Is a device “bricked” if it has a locked bootloader, official /e/ OS recovery and OS installed, but SPL/android verified boot prohibits the OS from loading? Does the device cease to be bricked when a official OS meeting the SPL is released and sideloaded to the device?
If you want to start fresh just use the android flash tool to get you to Android 15 located here: https://flash.android.com/welcome
Then use command line to go to eOS 15 official. eOS16 will be out soon enough. I do not believe the Pixel 8 is subject to the Google anti-rollback feature.
But @Jets the clue is in the title Pixel 8 shiba does have the May 2025 bootloader anti-rollback.
The post you are replying to is “post solution” but seeking an “Advanced primer” on some of the terms used in this rather complex situation.
So what I am saying is I don’t think the Pixel 8 is subject of the stock ROM anti-roll back feature, or at least it appears that way from the android tool page? Maybe I misunderstand the Android page?
So I just wonder if it is true that shiba has the anti-rollback?
Edit this is the warning I am seeing:
Warning: The May 2026 update for Pixel 10, 10 Pro, 10 Pro XL and 10 Pro Fold devices contains a bootloader update that increments the anti-roll back version for the bootloader. This prevents the device from rolling back to previous vulnerable versions of the bootloader. After flashing the May 2026 update on these devices you won’t be able to flash and boot older Android 16 builds.
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That is the May 2026 warning. The May 2025 problem is referenced in Post #1
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I sense a misunderstanding/miscommunication in the last couple posts.
This is exactly why I warned we need to be careful in defining what “locks” we’re talking about here.
If I felt the ~$300-400 were worth it, I’d buy another Pixel 8 and dick around with it/risk hard-bricking it for fun.
@Jets what I think you’re focusing on is the bootloader anti-rollback.
What @aibd appears to be focusing on is some other Service Patch Level/Android Verified Boot anti-rollback.
The former is focused solely on the bootloader. The latter is focused solely on the operating system/ROM.
At this time I believe if you do things poorly/without care and caution you can end up with a soft/hard bricked device in both cases, but it depends a lot on the order of operations (particularly bootloader locking).
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Just to keep this factual. I have been focusing on how @croulibri can most safely and easily install /e/OS as I just mentioned
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