What to do after flashing Android 13 on Pixel 6

With Android 13, Google made it so that the Pixel 6, 6 Pro and 6a cannot reinstall Android 12 to fix a security issue. To address this vulnerability, another issue may arise and Google has released instructions on how to avoid bricking your device if you flashed Android 13.

What’s different about the Android 13 update for the Pixel 6

A security vulnerability exists with the previous bootloader on the Pixel 6 series, and Android 13 makes it so that the vulnerable version bundled with Android 12 cannot be reinstalled.

But even after flashing an Android 13 factory image – which is different from sideloading an OTA image – on the Pixel 6 series and successfully updating, an Android 12 build remains on your phone. This is due to Android’s A/B (seamless) system updates, which are intended to provide redundancy:

A/B system updates use two sets of partitions called slots (usually slot A and slot B). The system runs from the current slot, while the partitions in the unused slot are not accessed by the running system during normal operation. This approach makes updates fault-tolerant by keeping the unused slot as a spare: if an error occurs during or immediately after an update, the system can roll back to the old slot and continue to have a working system.

As such, the “inactive slot contains an older bootloader whose anti-rollback version has not been increased.” This discrepancy can cause problems if you flash your device and something goes wrong with the installation. By design, Android will try to boot from the inactive slot, but that violates the vulnerability protection. Since it’s Android 12 (and the older bootloader), your phone won’t turn on.

If you flashed Android 13

On Thursday afternoon, Google provided instructions on how to prevent the problem from occurring. It involves flashing the inactive slot from Android 12 to Android 13. The simplest option is to sideload an OTA image – which updates the inactive slot – but steps for using factory images are also provided.

This process is primarily aimed at those (i.e. tinkerers) who want to flash their devices with either a factory or custom image (built from AOSP).

Meanwhile, in the coming days Google will update the Android Flash Tool – which flashes the active slot, like fastboot – with a prompt to flash the inactive slot with the Android 13 bootloader.

If you used Android 13 OTA

Those who sideloaded an Android 13 OTA image or accepted OTA on the device (which is Google’s recommended installation method) and don’t intend to blink (again, different from sideloading) their phones “don’t need to do anything for now.”

Castle A Castle B
Android 12 (July sec patch) Android 12 (June)
Android 12 (July) Android 13 (August)
Android 13 (September) Android 13 (August)
The active slot is in bold, with OTAs installed in the inactive slot

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

Kyle Bradshaw and Dylan Roussel contributed to this article.

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