What to do after flashing Android 13 on Pixel 6

With Android 13, Google made the Pixel 6, 6 Pro and 6a unable to reinstall android 12 to resolve a security issue. By patching this vulnerability, another issue could arise, and Google has released instructions on how to avoid tinkering with your device if you’ve flashed Android 13.

What’s different with Android 13 update for Pixel 6

A security vulnerability exists with the previous bootloader on the Pixel 6 series, and Android 13 makes the vulnerable version associated with Android 12 unable to be reinstalled.

However, even after flashing an Android 13 factory image – which is different from sideloading an image OTA – on Pixel 6 series and successful update, an Android 12 version remains on your phone. This is due to Android A/B system updates (transparent)which are intended to provide redundancy:

System A/B updates use two sets of partitions called slots (usually slot A and slot B). The system runs from the current slot while the partitions of the unused slot cannot be accessed by the running system during normal operation. This approach makes updates resilient to failures by keeping the unused location as a fallback: if an error occurs during or immediately after an update, the system can revert to the old location and continue to have a system functional.

As such, the “inactive slot contains an older bootloader whose anti-rollback version has not been incremented”. This incompatibility can cause problems if you flash your device and something fails during installation. By design, Android will try to boot from the idle location, but this defeats vulnerability protection. Since this is Android 12 (and the old bootloader), your phone won’t turn on.

If you flashed Android 13

Google Thursday afternoon instructions provided on how to prevent this particular problem from arising. This involves flashing the idle location from Android 12 to Android 13. The easiest option is to load an OTA image – which updates the idle location – but the steps for using factory images are also provided.

This process is primarily for those (i.e. DIYers) who are going to reflash their devices with a factory or custom image (built from AOSP).

Meanwhile, Google will update in the coming days the Android Flash Tool – which makes the active slot flash, like Quick Start – with a prompt to flash the idle location with the Android 13 bootloader.

If you used the Android 13 OTA

Those who charged aside – one treat without device / data wipe – an Android 13 OTA image or accepted the OTA on the device (which is Google’s recommended installation method) and don’t intend to flash (again, different from sideloading), their phones “don’t need to take any action yet”.

Slot A Slot B
Android 12 (July patch) Android 12 (June)
Android 12 (July) Android 13 (August)
android 13 (September) Android 13 (August)
The active location is in bold, with OTAs settling into the inactive location

The company also tells us that there is a very low chance of encountering the problem for the overwhelming majority of users with locked bootloaders. The next OTA (presumably the September security patch) or sideload will update the inactive location.

Kyle Bradshaw and Dylan Roussel contributed to this article.

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