Question Has anyone ever tried downgrading Android 13 to 12 via skipping flashing the bootloader: I have tried

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bush911

Senior Member
Oct 12, 2012
804
341
重庆
Google Nexus 5
Google Pixel
Hi there,

Just like the title says.
Xprivacylua won't' work on Android 13 for me. what I was wondering is whether I can downgrade without flashing the bootloader.

I am going to follow the following guide but am afraid to get a bricked phone:cautious:


Thank you all
------------------------add---

finally managed to downgrade to Android 12, just add --force before update:

fastboot --force update image-oriole-sq3a.220705.001.b2.zip (m phone is pixel6)

then reboot, then choose factory reset.
credits @Bunnehbunn
 
Last edited:

smokejumper76

Senior Member
Nov 28, 2014
170
53
If you do it, regardless if you succeed or fail, you and your phone shall forever be remembered. And this day
forth shall always be named bush911 Pixel 6 Pro Day. And it shall be written and stories will be told from one generation to the next.

If you do it, the inner Yoda in me tells me to tell you to make sure you flash BOTH slots. Godspeed.
 

bush911

Senior Member
Oct 12, 2012
804
341
重庆
Google Nexus 5
Google Pixel
If you do it, regardless if you succeed or fail, you and your phone shall forever be remembered. And this day
forth shall always be named bush911 Pixel 6 Pro Day. And it shall be written and stories will be told from one generation to the next.

If you do it, the inner Yoda in me tells me to tell you to make sure you flash BOTH slots. Godspeed.
You've made my day😁
I am going to wait and see for several days before proceeding as I just know how to flash-all, I have never flashed step by step or flashed to the specific slots.
 

roirraW "edor" ehT

Forum Moderator
Staff member
  1. I know that Android 12 worked just fine with Android 13's bootloader, but that was before I actually upgraded to 13. After I fully upgraded to 13, I wasn't willing to test downgrading everything but the bootloader since I would have to wipe in order to have app data be consistent with the Android version.
  2. I'm pretty sure in my thread a user (sooooo many posts this week since the update, it's all running together) that yesterday a user reported that downgrading everything but the bootloader worked just fine. Android 12 worked fine. If you do this, remember to wipe (and have a backup of anything you want to keep from your internal storage), and downgrade on both slots, not just your active slot.
 

Lughnasadh

Senior Member
Mar 23, 2015
3,907
4,186
Google Nexus 5
Huawei Nexus 6P
  1. I'm pretty sure in my thread a user (sooooo many posts this week since the update, it's all running together) that yesterday a user reported that downgrading everything but the bootloader worked just fine. Android 12 worked fine.
Oh, I have to find that post. I knew someone was talking about trying that but didn't see that they actually did. Let's see how good of a friend search really is to me 😆
 

bush911

Senior Member
Oct 12, 2012
804
341
重庆
Google Nexus 5
Google Pixel
  1. I know that Android 12 worked just fine with Android 13's bootloader, but that was before I actually upgraded to 13. After I fully upgraded to 13, I wasn't willing to test downgrading everything but the bootloader since I would have to wipe in order to have app data be consistent with the Android version.
  2. I'm pretty sure in my thread a user (sooooo many posts this week since the update, it's all running together) that yesterday a user reported that downgrading everything but the bootloader worked just fine. Android 12 worked fine. If you do this, remember to wipe (and have a backup of anything you want to keep from your internal storage), and downgrade on both slots, not just your active slot.
Is downgrading on both slots a must? I have just flashed Android 13 bootloader on both slots. For now chrome (stable, beta and development) keeps crashing. I can't even finish writing this reply on Chrome.
tried clearing the cache, restarting etc., ended up with no luck . It turned out that Chrome often closes itself within no more than 5 minutes of browsing after downloading to Android 12
Post before crashing
.
 

roirraW "edor" ehT

Forum Moderator
Staff member
Is downgrading on both slots a must?
If you want to run Android 12 instead of 13, and you've already flashed 13 to both slots, or at least 13's bootloader to both slots (which you should definitely do if you haven't), then yes, you should downgrade both slots and wipe to start fresh.

You can't expect both Android 12 and Android 13 to operate with the same app data, so having a different version of Android on the other slot isn't going to do you any favors.

I have just flashed Android 13 bootloader on both slots. For now chrome (stable, beta and development) keeps crashing. I can't even finish writing this reply on Chrome.
tried clearing the cache, restarting etc., ended up with no luck . It turned out that Chrome often closes itself within no more than 5 minutes of browsing after downloading to Android 12
Post before crashing
.
Try a factory reset?
 

roirraW "edor" ehT

Forum Moderator
Staff member
Oh, I have to find that post. I knew someone was talking about trying that but didn't see that they actually did. Let's see how good of a friend search really is to me 😆
Here my friend. Also in the OP.

Partial quote:
I tried this as soon as I upgraded to 13 and yes you can downgrade down to Android 12 after upgrading with no noticable issues. The radio and every other image but the bootloader can be downgraded. But I only tried 003, 004 July images for oriole so I don't know about anything lower personally.
 
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roirraW "edor" ehT

Forum Moderator
Staff member
Ok, you are now officially a better friend to me than search is. Sorry search... 🤪

Thank you!!!
You can join the ranks of such like my boss at work (where we use Google officially for everything including company mail). They chat me to ask me for a link to a particular file that's in Google Drive, or to find a particular email for them.

Just kidding about joining the ranks! :D You're welcome!
 
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Lughnasadh

Senior Member
Mar 23, 2015
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Huawei Nexus 6P
Here my friend. Also in the OP.

Partial quote:
I guess it would just as easy to remove the bootloader line from the flash-all.bat script and just use flash-all???

It's good to know for sure that we can downgrade though and that it's only the bootloader version that is important and not other parts of the OS.
 
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roirraW "edor" ehT

Forum Moderator
Staff member
I guess it would just as easy to remove the bootloader line from the flash-all.bat script and just use flash-all???
It's good to know for sure that we can downgrade though and that it's only the bootloader version that is important and not other parts of the OS.
Absolutely, I agree on both parts.
 
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enderdzz

New member
Aug 20, 2022
4
5
Hi, I have a question here, as long as I don't update the latest bootloader (>= 1.2 ?), it shouldn't trigger the anti rollback mechanism? My pixel 6 with Android 13 now has a bootloader version of oriole-slider-1.1-8167057, but the bootloader version in this official page has been updated to slider-1.2-8739948.

I pulled the AOSP 13 (branch android-13.0.0_r2), built it locally (userdebug mode), and flashed it without the bootloader because there is no bootloader.img in the build output. And the phone successfully booted.

I've never flashed the Android 13 factory image, so i got away with the risk of ARB?
 
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Namelesswonder

Senior Member
Jan 26, 2014
270
401
Google Pixel XL
Google Pixel 6 Pro
Hi, I have a question here, as long as I don't update the latest bootloader (>= 1.2 ?), it shouldn't trigger the anti rollback mechanism? My pixel 6 with Android 13 now has a bootloader version of oriole-slider-1.1-8167057, but the bootloader version in this official page has been updated to slider-1.2-8739948.

I pulled the AOSP 13 (branch android-13.0.0_r2), built it locally (userdebug mode), and flashed it without the bootloader because there is no bootloader.img in the build output. And the phone successfully booted.

I've never flashed the Android 13 factory image, so i got away with the risk of ARB?
I'm surprised with that old of a bootloader you were able to boot Android 13, you're running a bootloader from April. Also I'm surprised you weren't bricked after booting Android 13 because it does increment the anti-rollback counter.


I'm guessing your bootloader version is old enough to not have the bits implemented so it just doesn't care, but that's weird because the July Android 12 bootloaders do have the bits and will not load if the counter is incremented by Android 13.

I wouldn't recommend continuing to run like this and would update to the August Android 13 bootloader because there's no telling what might be happening wrong under the hood. Example is that the August Android 13 bootloader it is able to boot Android 12 but because of interface differences it is a broken experience.

So yeah if you're correct then it's possible you did get away with it as your firmware is too old to have implemented it. However this is not a supported firmware-software configuration.
 

enderdzz

New member
Aug 20, 2022
4
5
Thank you for your reply!
I'm surprised with that old of a bootloader you were able to boot Android 13, you're running a bootloader from April.
Yeah. This bootloader came from the factory image `oriole-sp2a.220405.004`.

I also noticed this piece of code, but I'm not sure if it was compiled into bootloader.img or boot.img? If it's in bootloader.img, that's a good explanation, because I didn't flash this version (after June) of bootloader so the A13 now isn't restricted by anti-rollback.

BTW I am also curious why the device is not flashed bootloader.img when running `fastboot flashall -w`, even though there is a compiled bootloader.img file in the output directory.
 
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Namelesswonder

Senior Member
Jan 26, 2014
270
401
Google Pixel XL
Google Pixel 6 Pro
Thank you for your reply!

Yeah. This bootloader came from the factory image `oriole-sp2a.220405.004`.


I also noticed this piece of code, but I'm not sure if it was compiled into bootloader.img or boot.img? If it's in bootloader.img, that's a good explanation, because I didn't flash this version (after June) of bootloader so the A13 now isn't restricted by anti-rollback.

BTW I am also curious why the device is not flashed bootloader.img when running `fastboot flashall -w`, even though there is a compiled bootloader.img file in the output directory.
That code is not in the bootloader, the bootloader is closed source. The code is part of the bootcontrolhal ([email protected]) on Android and runs on a successful boot of Android. The other code is the sysfs device being called by the HAL, that code is in the kernel.

I don't know if your device actually had the anti-rollback counter incremented, because a system monitor call is made and the source code for TZ/TEE/Titan are also closed source. Your device might've never incremented the counter because the firmware used by them just don't have the ability to, but it's just speculation.

And flashall doesn't flash bootloaders or radios, it only flashes Android system partitions defined by the product information. You can follow the steps here to flash them.
 

enderdzz

New member
Aug 20, 2022
4
5
That code is not in the bootloader, the bootloader is closed source. The code is part of the bootcontrolhal ([email protected]) on Android and runs on a successful boot of Android. The other code is the sysfs device being called by the HAL, that code is in the kernel.

I don't know if your device actually had the anti-rollback counter incremented, because a system monitor call is made and the source code for TZ/TEE/Titan are also closed source. Your device might've never incremented the counter because the firmware used by them just don't have the ability to, but it's just speculation.

And flashall doesn't flash bootloaders or radios, it only flashes Android system partitions defined by the product information. You can follow the steps here to flash them.
Thank you very much! I'm much more clear now.
 

Namelesswonder

Senior Member
Jan 26, 2014
270
401
Google Pixel XL
Google Pixel 6 Pro
Thank you very much! I'm much more clear now.
That's good.
Have a question, while you were on Android 13 with the Android 12 bootloader, was everything working right? Nothing crashing or throwing errors? With the Android 13 bootloader on Android 12 having issues with DRM and web browsers crashing it would be interesting to know if the same was also true for you when you were on the opposite scenario.
 

enderdzz

New member
Aug 20, 2022
4
5
That's good.
Have a question, while you were on Android 13 with the Android 12 bootloader, was everything working right? Nothing crashing or throwing errors? With the Android 13 bootloader on Android 12 having issues with DRM and web browsers crashing it would be interesting to know if the same was also true for you when you were on the opposite scenario.
Yes, I'm also interested in this topic.

I've only tested webview browser tester 101.0.4951.61 and NNAPI. No problems found so far. I will update here if I encounter any new problems :)

I'll experience it deeply, won't flash another system or bootloader for a while. Since I flashed the userdebug version, which I think is not as feature-rich as the factory image, but it let me have root access.

I also checked `dmesg` info and didn't find anything abnormal except that it keeps reporting `init: Control message: Could not find 'aidl/android.hardware.biometrics.fingerprint.IFingerprint/default' for ctl .interface_start from pid: 467 (/system/bin/servicemanager)`, I think it's not a big deal. And no useful log about the anti-rollback counter, which maybe needs some reverse engineering.
 

Namelesswonder

Senior Member
Jan 26, 2014
270
401
Google Pixel XL
Google Pixel 6 Pro
Yes, I'm also interested in this topic.

I've only tested webview browser tester 101.0.4951.61 and NNAPI. No problems found so far. I will update here if I encounter any new problems :)

I'll experience it deeply, won't flash another system or bootloader for a while. Since I flashed the userdebug version, which I think is not as feature-rich as the factory image, but it let me have root access.

I also checked `dmesg` info and didn't find anything abnormal except that it keeps reporting `init: Control message: Could not find 'aidl/android.hardware.biometrics.fingerprint.IFingerprint/default' for ctl .interface_start from pid: 467 (/system/bin/servicemanager)`, I think it's not a big deal. And no useful log about the anti-rollback counter, which maybe needs some reverse engineering.
If WebView applications didn't crash within minutes of launching them then that means the DRM library should either be working or just not segfaulting like it does with Android 12 on 13 bootloader.

The fingerprint scanner HAL not working is completely understandable, part of the bootloader flash also carries the fingerprint scanner's firmware, and we know that one of the big things with Android 13 is that the fingerprint scanner is somewhat more reliable, so it definitely has changed between Android 12 to 13.

Interesting stuff, will be cool to see where it can go, but man is it sketchy to recommend people still on Android 12 to downgrade to April and then try flashing the Android 13 system images, real possibility of making bricks.
 
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  • 8
    If you do it, regardless if you succeed or fail, you and your phone shall forever be remembered. And this day
    forth shall always be named bush911 Pixel 6 Pro Day. And it shall be written and stories will be told from one generation to the next.

    If you do it, the inner Yoda in me tells me to tell you to make sure you flash BOTH slots. Godspeed.
    6
    Hi there,

    Just like the title says.
    Xprivacylua won't' work on Android 13 for me. what I was wondering is whether I can downgrade without flashing the bootloader.

    I am going to follow the following guide but am afraid to get a bricked phone:cautious:


    Thank you all
    ------------------------add---

    finally managed to downgrade to Android 12, just add --force before update:

    fastboot --force update image-oriole-sq3a.220705.001.b2.zip (m phone is pixel6)

    then reboot, then choose factory reset.
    credits @Bunnehbunn
    4
    1. I know that Android 12 worked just fine with Android 13's bootloader, but that was before I actually upgraded to 13. After I fully upgraded to 13, I wasn't willing to test downgrading everything but the bootloader since I would have to wipe in order to have app data be consistent with the Android version.
    2. I'm pretty sure in my thread a user (sooooo many posts this week since the update, it's all running together) that yesterday a user reported that downgrading everything but the bootloader worked just fine. Android 12 worked fine. If you do this, remember to wipe (and have a backup of anything you want to keep from your internal storage), and downgrade on both slots, not just your active slot.
    3
    1. I'm pretty sure in my thread a user (sooooo many posts this week since the update, it's all running together) that yesterday a user reported that downgrading everything but the bootloader worked just fine. Android 12 worked fine.
    Oh, I have to find that post. I knew someone was talking about trying that but didn't see that they actually did. Let's see how good of a friend search really is to me 😆
    3
    Ran a couple tests to see what was working and what was failing.

    OEM A12 (raven-sq3a.220705.004-factory-112d4f32) on A13 Bootloader
    Step 1. Make sure both Slots have A13 w/A13 Bootloader
    Step 2. Make full backup of Apps and Data
    Step 3. Install with fastboot --force update
    Step 4. Sign-into Play Store
    Step 5. Install Webview Canary
    Step 6. DRM specific items fail with unable to access errors

    LOS 19.1 on A13 Bootloader
    Step 1. Make sure both Slots have A13 w/A13 Bootloader
    Step 2. Wipe
    Step 3. Install LOS 19.1
    Step 4. Boot Slot B (Slot A fails to boot)
    Step 5. Install DRM testing tools. Got same issue as OEM A12

    At end of process re-wiped and re-installed A13 Update.

    ***EDIT***
    Forgot Install of ROM step in OEM ROM trial write-up.