General 🛑❗⚠️ WARNING! Read this before your initial upgrade to Android 13!⚠️❗🛑

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V0latyle

Forum Moderator
Staff member
***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 Tensor devices, regardless of whether or not you're rooted!

What this means:

Once Android 13 Stable boots, 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 slider-1.2-8739948. 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
 
Last edited:

Namelesswonder

Senior Member
Jan 26, 2014
432
731
Google Pixel XL
Google Pixel 7 Pro
Android 12 party is over, DRM APEX isn't functional when the Android 13 bootloader is installed.

You won't be able to use WebView or browsers, and anything that wants to check DRM like streaming applications are going to crash.

Maybe at some point a developer can look into cooking up a custom Android 12 ROM with Android 13 APEXs or patched ones.
 

heij20032003

Member
Mar 23, 2009
25
9
From the Pixel Images page:
View attachment 5690651

Once Android 13 boots, it updates an anti-rollback counter in the device hardware to prevent rolling back the bootloader. There is potential for a brick if you do not flash both bootloader_a and bootloader_b, such as during an OTA update, and the device bootloops back to the old Android 12 bootloader.

Advice: For those of you updating manually, flash bootloader to both slots regardless of how you intend to upgrade.

Q: How do I make sure my LOCKED bootloader doesn't brick? After successfully updating, sideload the Android 13 OTA, which automatically installs to the other slot.

Q: How do I make sure my UNLOCKED bootloader doesn't brick? BEFORE updating, flash the bootloader to BOTH slots:
Code:
fastboot flash bootloader --slot=all <bootloader image>

Q: WIll the new bootloader prevent me from flashing and running Android 12? The short answer is YES, for now. 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 I have used the basic function of Pixel Flasher to flash A13 successfully, what else should I do in this case?
 
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KHANrad_SIN

Senior Member
Jul 4, 2014
274
98
So the OP says to flash the new bootloader to both slots BEFORE updating. The thing is, I already updated to A13 and I didn't flash to both slots. Everything is working fine for me but my question is will this affect me later on? possible when I flash the next monthly update?

Also, can I simply flash the new bootloader to both slots right now without it affecting anything?
 

Lughnasadh

Senior Member
Mar 23, 2015
5,497
6,562
Google Nexus 5
Huawei Nexus 6P
So the OP says to flash the new bootloader to both slots BEFORE updating. The thing is, I already updated to A13 and I didn't flash to both slots. Everything is working fine for me but my question is will this affect me later on? possible when I flash the next monthly update?

Also, can I simply flash the new bootloader to both slots right now without it affecting anything?
You should flash the bootloader to the inactive slot now.
 

sjgoel

Senior Member
I flashed the Android 13 update via Pixel Flasher as usual, all good and my phone is working fine.

Should I worry if the bootloader was flashed to both slots, OR not since all went well and the phone is working normally on A13?
 

fil3s

Senior Member
Aug 30, 2014
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V0latyle

Forum Moderator
Staff member
I flashed the Android 13 update via Pixel Flasher as usual, all good and my phone is working fine.

Should I worry if the bootloader was flashed to both slots, OR not since all went well and the phone is working normally on A13?
Did you read the OP? It's up to you whether you want to risk a brick should the device boot loop.

View attachment 5691443
Nice, thank you.
 

foobar66

Senior Member
Jan 8, 2011
2,142
2,230
Brussels
Google Pixel 6 Pro
After having upgraded to A13 (retaining root and data), I flashed the bootloader to both slots (--slot=all).
Then, using fastboot, changed the active slot (from B to A) and 'updated' (full update) the 'other' (nonactive) slot (A) as well.
All went fine.
Then I changed the active slot back to B.
Then I rebooted ... Google logo appeared ... few seconds later phone rebooted into bootloader (without any warning).
Reboot again ... same ... Google logo appears and a few seconds later reboot to bootloader.

Sigh ... I was slightly in panic ;-)

Then re-updated the (original) B slot again with A13.

After that upgrade to B (which already contained a working A13) all was fine.

Really weird, I don't think I did anything wrong or in the wrong order, so I don't understand why it did not want to boot into a previously working slot (B).

Anyway ... now all is fine again.
 

Lughnasadh

Senior Member
Mar 23, 2015
5,497
6,562
Google Nexus 5
Huawei Nexus 6P
After having upgraded to A13 (retaining root and data), I flashed the bootloader to both slots (--slot=all).
Then, using fastboot, changed the active slot (from B to A) and 'updated' the 'other' (nonactive) slot (A) as well.
All went fine.
Then I changed the active slot back to B.
Then I rebooted ... Google logo appeared ... few seconds later phone rebooted into bootloader (without any warning).
Reboot again ... same ... Google logo appears and a few seconds later reboot to bootloader.

Sigh ... I was slightly in panic ;-)

Then re-updated the (original) B slot again with A13.

After that upgrade to B (which already contained a working A13) all was fine.

Really weird, I don't think I did anything wrong or in the wrong order, so I don't understand why it did not want to boot into a previously working slot (B).

Anyway ... now all is fine again.
Yeah, that's normal when doing it like that. Think you need to actually boot into the new slot first.
 
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  • 28
    ***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 Tensor devices, regardless of whether or not you're rooted!

    What this means:

    Once Android 13 Stable boots, 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 slider-1.2-8739948. 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
    8
    Android 12 party is over, DRM APEX isn't functional when the Android 13 bootloader is installed.

    You won't be able to use WebView or browsers, and anything that wants to check DRM like streaming applications are going to crash.

    Maybe at some point a developer can look into cooking up a custom Android 12 ROM with Android 13 APEXs or patched ones.
    6
    Source? This would be nice. I still think Pixel Flasher is superior in most ways


    Screenshot_20220821-005234.png
    5
    FYI: Even though Android Flash Tool does not flash the whole image to both slots, they have added an option to flash the A13 bootloader to the inactive slot. This may be the easiest option when updating to A13 from A12.

    Just to be clear, when updating to A13 from A12 a prompt will show up asking whether you want to also flash the bootloader to the inactive slot as well. It doesn't show up in the regular tick boxes.


    Screenshot from 2022-08-24 14-39-11.png
    3
    understood. is it definitely confirmed that none of the betas had ARB?
    I don't know the answer to that. I also didn't participate in the Betas in any way at all other than sharing links for each new Beta version.

    personally I'm not willing to commit to no going back with a13 until I know all my critical apps are compatible.
    I haven't had any issues with any of my apps, but everyone's usage is different. Technically speaking, I can say that for a day or two after I flashed Android 13 Stable, the root/Xposed-based AOSP Mods only partially worked with Android 13, but it's since been updated to fully support all the features on Android 13 that I cared about, and then some.