Google provides more guidance for Pixel 6 users that flashed Android 13
In order to fix a security flaw, Google modified it so that the Pixel 6, 6 Pro, and 6a cannot reinstall Android 12 with Android 13. Google has provided instructions on how to prevent bricking your smartphone if you flashed Android 13 in order to remedy that vulnerability.
What has changed with the Pixel 6’s Android 13 update
The previous bootloader on the Pixel 6 series has a security flaw, and Android 13 prevents users from reinstalling the vulnerable version linked to Android 12.
However, even after successfully updating your Pixel 6 series device with an Android 13 factory image (which is distinct from sideloading an OTA image), an Android 12 build still exists on your device. This is a result of the A/B (seamless) system updates for Android, which are designed to add redundancy:
A/B system upgrades employ two slots, or sets of partitions (normally slot A and slot B). The partitions in the unused slot are not accessed by the running system during regular operation; instead, the system operates from the currently occupied slot. By keeping the unused slot available as a backup, this method makes updates fault-tolerant: The system can rollback to the previous update slot if an issue happens during or right after it, maintaining a functional system.
Consequently, “the inactive slot has an older bootloader whose anti-rollback version has not been increased.” If you flash your device and the install fails, that mismatch could lead to issues. Android will attempt to boot from the inactive slot by design, however that violates the vulnerability protection. Your phone won’t power on because Android 12 (and an older bootloader) are both installed.
Having installed Android 13
On Thursday afternoon, Google offered advice on how to prevent that specific problem from occurring. It entails flashing Android 12 to Android 13 in the idle slot. The most straightforward method is sideloading an OTA image, which updates the inactive slot, however instructions are also supplied for utilising factory images.
Those (i.e. tinkerers) who plan to reflash their devices with either a factory or custom image should focus on this procedure (built from AOSP).
The Android Flash Tool, which flashes the active slot like fastboot, will receive an update from Google in the upcoming days that will include a prompt to flash the inactive slot with the Android 13 bootloader.
If you used the OTA for Android 13
People who accepted the on-device OTA (which is Google’s recommended install method) or sideloaded an Android 13 OTA image without wiping their devices or data “don’t need to take any action for now,” according to Google.
Slots A and B
12 Android (July sec patch)
12 Android (June)
12 Android (July)
13 Android (August)
13 Android (September)
13 Android (August)
OTAs install in the inactive slot, with the active slot highlighted in bold.
The bulk of users with locked bootloaders, according to the business, have a very minimal possibility of experiencing the problem. The inactive slot will be updated by the subsequent OTA (likely the September security patch) or sideload.