@V0latyle I booted to the inactive slot (see below) and it was on the very same version 12.0.0 (SQ1A.211205.008, Dec 2021). The full factory image comes with a Google warning I decided not to ignore "Note that it's typically easier and safer to sideload the
full OTA image instead."
View attachment 5507739
I'm confused, are you trying to update to January?
Is either slot rooted?
The reason why OTA updates are generally "safer" is because they install to the inactive slot; if booting the inactive slot fails for whatever reason, the system will revert to the original slot.
More details here
Basically this is how it works:
- Pixel devices have A/B slots
- While system is running on slot A, it can download and install OTA update to Slot B, then command a reboot
- If boot is successful, Slot B is set as active; the next OTA will be installed to Slot A
- If boot is not successful, system reboots to Slot A (the non-updated slot) and the update can be attempted again.
The idea here is that the device has a degree of "self recovery" wherein it will revert to a usable state if the update fails for whatever reason. This works regardless of whether the bootloader is unlocked.
Flashing the factory image only works on an unlocked bootloader for two reasons:
- Partitions are flashed directly from PC
- Partition images cannot be verified for integrity and authenticity
ADB sideload basically works the same way as the seamless system update, just from recovery. The OTA image is checked against a known hash before it is flashed.
All that being said, it's pretty much moot for those of us with unlocked bootloaders, to a degree - if something goes wrong, it's most likely your own fault, and you have to fix it yourself - the device won't be able to fix it for you. For instance, if something goes wrong with the factory flash for whatever reason, you'll have to figure out why and ensure a subsequent flash is successful. Or, if you accidentally wipe data during the update, you're screwed - there is no way to recover user data once wiped. The OTA on the other hand never touches user data. The factory update in of itself doesn't either - the update
process might, specifically the script included, as it incorporates the
-w
option by default to wipe data. So, if User Johnny Knucklehead skims over a few guides that aren't specific to his device, and decides to update by downloading the factory image and running the script without editing or learning the commands...then he'll have to start from scratch when things go wrong.