General PSA: Pixel 6a Bootloader Anti-Rollback

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V0latyle

Forum Moderator
Staff member
hi thanks for the tip. i think the topic is already related to the matter, i should have made it more general.

i understood that bootloader 1.2 belongs to android 12 and bootloader 1.3 to android 13. the thread does warn against combining an old bootloader with android 13.
Says who? I literally just said that the bootloader version number has nothing to do with the Android version.

The bootloader that was packaged with the first stable Android 13 release was slider-1.2-8739948 for the Pixel 6 / 6 Pro, and bluejay-1.2-8893284 for the 6a.

Edit: Just downloaded the February update for the Bluejay. Bootloader version is 1.2-9288097. There is no 1.3.
The question would be whether Android 13 and the installation of a custom ROM is also compatible with bootloader 1.2.
Do you mean to ask whether a custom Android 13 build would run on the Android 12 bootloader? No idea.
 
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moped2000

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Mar 9, 2017
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Says who? I literally just said that the bootloader version number has nothing to do with the Android version.

The bootloader that was packaged with the first stable Android 13 release was slider-1.2-8739948 for the Pixel 6 / 6 Pro, and bluejay-1.2-8893284 for the 6a.

Edit: Just downloaded the February update for the Bluejay. Bootloader version is 1.2-9288097. There is no 1.3.

Do you mean to ask whether a custom Android 13 build would run on the Android 12 bootloader? No idea.
Ok, then I must have misunderstood. In the first post the code has been shared how to check it and it says bootloader version 1.3. This is why I thought the 1.2 is the older variant and was wondering why my phone didn't install 1.3 when I updated to A13. Then I still need to figure out why recovery doesn't work when I flash it, but then that actually belongs in the appropriate thread. Thanks
 

V0latyle

Forum Moderator
Staff member
Ok, then I must have misunderstood. In the first post the code has been shared how to check it and it says bootloader version 1.3. This is why I thought the 1.2 is the older variant and was wondering why my phone didn't install 1.3 when I updated to A13. Then I still need to figure out why recovery doesn't work when I flash it, but then that actually belongs in the appropriate thread. Thanks
That was supposed to simply be an example, but I understand how it can be confusing. My mistake, I'll update the OP with the "real" versions.
 

AtrixHDMan

Senior Member
Mar 3, 2015
744
134
I bootloader unlock my Pixel 6a and I want to go back to Android 12.Can I do that and the bootloader stay unlocked.Also is it safe.
 

AtrixHDMan

Senior Member
Mar 3, 2015
744
134
The bootloader will stay unlocked until you relock it. There is nothing on the Android 13 bootloader that prevents you from running a custom ROM. However, the factory Android 12 builds will not run properly.
I understand and just wanted to go back to the lasted Android 12 factory rom.Thanks.
 

d4guser

Member
May 25, 2023
16
3
I just got the Pixel 6a, it has the same bootloader version on slots A and B:

bluejay-1.2-8893284

And it's running Android 13 build TP1A.220624.021.A1 - August 5 2022 update.

Am I likely safe to root the phone with the Pixel 6a guide here: https://www.xda-developers.com/how-...root-magisk-google-pixel-6a/#unlockbootloader

Or do I need to do something special as per here: https://www.xda-developers.com/google-pixel-6-pro-6a-android-13-qpr2-beta-root/

The bootloader version is the 'safe' version mentioned in the first post by OP. However, It's my first time doing this, so just making sure.
 
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d4guser

Member
May 25, 2023
16
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The anti-rollback has nothing to do with root, even bone stock devices could be bricked if the update from 12 to 13 fails.

Yes, you are safe.
Thanks for the fast reply, just wondering if this would be the guide I should follow?

Just asking because I saw a newer guide relating to 'help from the Pixel 7 on the latest Android 13 beta', but I don't think I have a beta build based in the build no.


TP1A.220624.021.A1
 

V0latyle

Forum Moderator
Staff member
Thanks for the fast reply, just wondering if this would be the guide I should follow?

Just asking because I saw a newer guide relating to 'help from the Pixel 7 on the latest Android 13 beta', but I don't think I have a beta build based in the build no.
Yes, that article is correct. Make sure you use Magisk 25.2.

If you aren't using a Pixel 7 and aren't running the beta, how would that be relevant?
 

d4guser

Member
May 25, 2023
16
3
That's okay, we all have to start somewhere.

I never wrote a guide explicitly for the 6a, but the process for the Pixel 6 is the same.

You can find that guide here
Thanks, I'll read over this. In the other guide, it says "Find the matching build number on the factory image download page and download that file." However, the build no. on my device, TP1A.220624.021.A1, does not appear on the page they link to for downloading A13 (https://www.xda-developers.com/how-to-download-android-13/#android-13-pre-qpr2-stable-builds).

I was wondering does this mean I need to update the A13 version on the device first, or can I just download the newest version from that link?

Apologies if this isn't a discussion for this forum.
 

d4guser

Member
May 25, 2023
16
3
Thanks, I'll read over this. In the other guide, it says "Find the matching build number on the factory image download page and download that file." However, the build no. on my device, TP1A.220624.021.A1, does not appear on the page they link to for downloading A13 (https://www.xda-developers.com/how-to-download-android-13/#android-13-pre-qpr2-stable-builds).

I was wondering does this mean I need to update the A13 version on the device first, or can I just download the newest version from that link?

Apologies if this isn't a discussion for this forum.
I actually found the right build no. from a link in your guide at (https://developers.google.com/android/images)
So I guess this is what I should use. It's a 'Factory image', as mentioned in your guide.

1685019162400.png
 

V0latyle

Forum Moderator
Staff member
I actually found the right build no. from a link in your guide at (https://developers.google.com/android/images)
So I guess this is what I should use..

View attachment 5918783

This is how the naming convention works:
TP1A is the main Android version. T for Android 13 "Tiramisu", P1A for the subversion.
220624 is the build date - June 24, 2022, even though this update was released in August. This is nearly a year old.

I recommend you use the latest one: TQ2A.230505.002
 
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d4guser

Member
May 25, 2023
16
3
This is how the naming convention works:
TP1A is the main Android version. T for Android 13 "Tiramisu", P1A for the subversion.
220624 is the build date - June 24, 2022, even though this update was released in August. This is nearly a year old.

I recommend you use the latest one: TQ2A.230505.002
Ok, good to know what the names actually mean. So even though that first guide says to find the factory image with the matching build number, I take it that's not actually required, a new stable one is good
 

V0latyle

Forum Moderator
Staff member
Ok, good to know what the names actually mean. So even though that first guide says to find the factory image with the matching build number, I take it that's not actually required, a new stable one is good
No, it's not required. You can update your device and root it at the same time using the factory image.

While I highly encourage you to learn to do this "long hand" using ADB, you may find using PixelFlasher much easier.
 

d4guser

Member
May 25, 2023
16
3
No, it's not required. You can update your device and root it at the same time using the factory image.

While I highly encourage you to learn to do this "long hand" using ADB, you may find using PixelFlasher much easier.
Yeah, I saw that recommended in your guide. I do want to learn this the ADB way though.

Truly appreciate your help
 
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  • 18
    ***Note: THIS IS NOT A ROOT GUIDE. For updating and root instructions, check out my guide here.***

    From the Pixel Images page:
    P6 AntiRollBack.png


    This applies to ALL Pixel 6 devices, regardless of whether or not you're rooted!

    This does NOT affect other Pixel generations, and the Android 14 update did not increment the bootloader anti-rollback.

    What this means:

    Once Android 13 Stable boots after the FIRST update to Android 13, it updates an anti-rollback counter in the device hardware to prevent rolling back the bootloader. This will prevent previous versions of the bootloader from starting.

    Why this is a problem:
    The OTA only updates one slot, then reboots into that slot. It does not update both slots at once. If there is a boot failure after updating to Android 13, the device may attempt to "recycle" back to the old slot. If this other slot has a previous version of the bootloader, the bootloader will not start, rendering the device a brick.

    How do I make sure this doesn't happen to me?

    If you updated via OTA, simply sideload the OTA again. Since you are currently on the Android 13 slot, this will overwrite your old Android 12 slot with the new bootloader.
    If you have an unlocked bootloader and prefer to update using the factory image, you can flash the bootloader to both slots:
    fastboot flash bootloader --slot=all <bootloader image> It's highly recommended you do this BEFORE updating, but if you didn't, do it as soon as possible.

    I've updated several times since the August 2022 update, am I still at risk?
    If you've updated via OTA at least once since you first updated to Android 13, you should be fine. Instructions to check bootloader versions are further down this post.

    The initial Android 13 release bootloader version is bluejay-1.2-8893284. As long as your bootloader is equal to or higher than this, you should be fine.

    What if I was on the Android 13 Beta?
    Same as above - the beta did not incorporate the anti-rollback, and the beta bootloaders are still considered "old".

    Will the new bootloader prevent me from flashing and running Android 12?
    The short answer is YES. Android 12 will not run properly on the Android 13 bootloader. Contrary to what the warning above says, you CAN flash Android 12 on the Android 13 bootloader, and though it will boot, it will not run properly. See this post.

    If you MUST use Android 12, you can use a Developer Support Image.

    How do I check my current bootloader version?
    Code:
    adb reboot bootloader #Reboots device to bootloader.
    
    fastboot getvar current-slot #Outputs current slot, should also be visible on the device screen: "Boot slot"
    
    fastboot getvar version-bootloader #Outputs current slot's bootloader version, should also be visible on device screen "Bootloader version"
    
    fastboot --set-active=a or b #Use this to switch to the inactive slot - if current slot is A, set to B or vice versa.
    
    fastboot getvar current-slot
    
    fastboot getvar version-bootloader
    
    fastboot --set-active=b or a (set to original slot) #Set active slot back to what it was before.  If you started on slot A, make sure you switch back to slot A.
    
    fastboot getvar current-slot
    
    fastboot continue #Commands device to resume boot, same function as selecting "Start" in the bootloader menu.
    
    #So as an example:
    fastboot getvar current-sot
    >current-slot: a
    
    fastboot getvar version-bootloader
    >version-bootloader: slider-1.2-8739948
    
    fastboot --set-active=b
    >Setting current slot to 'b'
    
    fastboot getvar version-bootloader
    >version-bootloader: slider-1.2-8739948
    
    fastboot --set-active=a
    >Setting current slot to 'a'
    
    fastboot continue
    9
    That would be the scoped storage sucking up resources/battery to make you feel safe...
    Android 10 is ok, 11 so-so, 12 sucks and along comes 13 beta. Yeah that'll work.
    Blame Gookill for this fubar.
    I mean...I've kinda liked A12. But to each his own.

    You'd probably rather run command line Linux on your phone, you old bastard lol
    7
    1000% fake comment.
    7
    This is such BS. Drama
    @blackhawk is entitled to his opinion, just as you are. Remember to keep your conduct civil and respectful:
    2.3 Flaming / Lack of respect: XDA is about sharing and this does not involve virtual yelling (flaming) or rudeness. Flaming or posting with a lack of respect is unacceptable. Treat new members in the manner in which you would like to have been treated when you were a new member. When dealing with any member, provide them with guidance, advice and instructions when you can, showing them respect and courtesy. Never post in a demanding, argumentative, disrespectful or self-righteous manner.