Problem flashing stock image

[Horgar]

I have UB and rooted with magisk 20.1. I rooted the October build by patching the boot image using magisk. I try to flash the new November stock image and it fails. It says
Writing boot
Failed (failed to write to partition Not found)

I think it may be connected to booting into slot a or b. Maybe?
Can anybody help?

 

[ctfrommn]

You already took the November OTA or are you still on October?

 

[Horgar]

You already took the November OTA or are you still on October?

I'm on October trying to flash November

 

[ctfrommn]

Pretty sure you cant flash the boot image alone. I always flash the stock boot for the build Im currently on then take the OTA. I think there is a new bootloader for November. Not 100% on that though.

 

[Horgar]

I'm just trying to flash the full factory November stock image. I downloaded it, unzip it, plug in the phone in fastboot and double click the run me bat file.
This has always been fine before but I am new to pixel 3a and have only done this once before, on October build. But I came from an original pixel so I've spent 2 years updating that in this way.
I can't work out why the flash is failing.

 

[ctfrommn]

Try flashing the stock October boot.img then try updating. Ive never been successful flashing an OTA or factory image over a patched boot.

 

[Horgar]

Try flashing the stock October boot.img then try updating. Ive never been successful flashing an OTA or factory image over a patched boot.

I've tried flashing October factory image and get the exact same result. Not sure what else to try.

 

[Horgar]

Try flashing the stock October boot.img then try updating. Ive never been successful flashing an OTA or factory image over a patched boot.

Sorry just reread your post. Will try and reflash boot IMG. I do that with fastboot flash boot.img?
Thanks

 

[ctfrommn]

Yes.... fastboot flash boot boot.img

 

[Horgar]

Yes.... fastboot flash boot boot.img

Have tried reflashing boot.img and still won't update ota and same result trying to flash factory image. Any other ideas? And thanks very much for your help

 

[Horgar]

Try flashing the stock October boot.img then try updating. Ive never been successful flashing an OTA or factory image over a patched boot.

Do I need to flash boot.img to both slots a and b? If so how do I do that?

 

[ctfrommn]

I only ever flash the one in use.

Just fastboot flash boot boot.img is all you need.


Your can also always just clean flash the OTA. Just download it, factory reset, adb sideload the OTA in recovery.
I've done that a few times now.

 

[Horgar]

I only ever flash the one in use.

Just fastboot flash boot boot.img is all you need.


Your can also always just clean flash the OTA. Just download it, factory reset, adb sideload the OTA in recovery.
I've done that a few times now.

Thanks. Will try things tomorrow. It's late here in London. But I can't get a twrp.img to work. It doesn't seem to mount the system and I can't flash anything. Have you got twrp to work? I'll come back to you in about 18hrs if that's ok?

 

[ctfrommn]

TWRP doesn't work with Q. Just use stock recovery to sideload.

 

[Horgar]

TWRP doesn't work with Q. Just use stock recovery to sideload.

Ok, will try when I get home from work. Does the OTA update contain a boot.img? Is that what I need to patch to root again?
Thanks very much

 

[ctfrommn]

Ok, will try when I get home from work. Does the OTA update contain a boot.img? Is that what I need to patch to root again?
Thanks very much

Yes, OTA and factory images are essentially the same thing just packaged differently.

And the easiest way to reroot is to just download and repatch the new stock image, or flash a custom pre patched kernel.

 

[sic0048]

Ok, will try when I get home from work. Does the OTA update contain a boot.img? Is that what I need to patch to root again?
Thanks very much

The OTA zip is packaged differently and does not include a boot.img file that we can use. (I'm sure it must be in there somewhere, but not in a usable form). Therefore you must download the "Factory Image" from Google. Unzip it, open it where you will find another zip file inside. Open that second zip file and you will find the boot.img file there. Move that boot.img file to your phone so that Magisk can access it and to modify it.

https://developers.google.com/android/images

 

[s.country]

Ok, will try when I get home from work. Does the OTA update contain a boot.img? Is that what I need to patch to root again?
Thanks very much

FYI here are the steps I took to update my rooted 3a this morning:
1. in Magisk Manager select Uninstall and select restore images (I did this because I kept getting a 'installation error' on the OTA page)
2. Like an idiot I rebooted my phone, do not reboot! So I had to reinstall magisk
2a. copy the boot.img of Oct to my phone to have it patched by magisk
2b. fastboot flash boot boot_patched.img
3. the OTA downloaded while I was on the stock boot.img so I just followed the magisk instructions to install the OTA in the other partition

Next month I'll just jump from step 1 to 3 and carry on being rooted.

 

[ctfrommn]

The simplest way to update when youre rooted is to......

Reflash the stock boot from the current build youre on
Take the OTA directly on the phone
Download stock image from new build and move it to phone
Patch with Magisk and move to your PC
Fastboot flash boot boot.img

Ive done this for the last 3 updates and it works perfectly every time......I obviously substitute my kernel for the patched boot but the process is the same. I find this far simpler than messing with Magisk

 

[Horgar]

Thanks for all the suggestions but I still cannot update.
I have tried restoring boot.img
data reset from recovery
relocking bl - ota fails
Unlocking bl again - won't flash using ADB

There is no problem with the phone being recognised on ADB, the flash Just fails as the screen shot in my opening post. I'm thinking it may be connected to needing to flash to the inactive slot.
Anyone got any ideas?