Due to a security flaw, the Pixel 6 series cannot return to Android 12 after updating to Android 13 [U].
Google recently released Android 13 for Pixel devices, and the update is currently rolling out to devices. Owners of the Pixel 6 series, however, cannot revert to Android 12 so Android 13 is virtually a permanent upgrade.
Android upgrades are typically reversible, allowing you to manually sideload the update and install an earlier version. This always necessitates a phone reset and data loss, but it is a process that is doable.
However, Android 13 prevents the Pixel 6, Pixel 6 Pro, and Pixel 6a from rolling back to Android 12 releases. Users will not be able to downgrade to Android 12 after installing this new version, according to a statement made by Google on the website where it hosts Factory Images.
Attention: The bootloader update in the Android 13 update for the Pixel 6, Pixel 6 Pro, and the Pixel 6a increases the anti-rollback version. You won’t be able to flash earlier Android 12 builds on these devices after flashing an Android 13 build.
The reason for the change, which is an unprecedented action by Google, is a new bootloader upgrade that “increments the anti-roll back version.” Generally speaking, Google has been using this security feature in Android for a number of years to stop the implementation of attacks from earlier software versions on devices.
Update 8/16: Google has stated the cause of the inability of the Pixel 6, Pro, and Pixel 6a to return to Android 12. Google claims that the bootloader version previously in use had a security problem, which was discovered by security researcher @flawedworld and mentioned in the Android Flash Tool (and highlighted by Mishaal Rahman).
The Google notice reads:
WARNING: You cannot revert to an earlier Android build after flashing this.
The bootloader on your device is functioning in a vulnerable state. Your device’s anti-rollback counter will be increased after flashing this build to stop future flashes of outdated, vulnerable bootloaders on the device. This will stop Android 12 releases from being flashed.
Most users won’t typically have a problem with this, but it’s still fascinating. It seems plausible to presume that this may have something to do with Google Tensor given the devices it impacts. In any event, please be aware that updating a Pixel 6 series gadget to Android 13 is essentially irreversible.
How to install Android 13 on a Google Pixel is covered in more detail below.
Google releases Android 13, which is now available for Pixel phones.
These smartphones will feature Android 13 thanks to OnePlus.