[Google Pixel 6] HypromanGT:
Going out of my mind trying to update from SQ3A.220705.003.A3 to the September one (that also means going from A12 to A13) o_O

I've followed the update A13-specific notes: Uninstall Magisk, reboot, then went to System Updates.

The update fails after a short period of time with "Installation problem". I am attaching the full logcat of "update_engine"; here are the ERROR bits:

09-18 15:19:47.954 954 954 E update_engine: [ERROR:cleanup_previous_update_action.cc(298)] Previous update has not been completed, not cleaning up
09-18 15:19:49.238 954 954 E update_engine: [ERROR:partition_writer.cc(608)] Unable to open ECC source partition boot, file /dev/block/platform/14700000.ufs/by-name/boot_b: Success (0)
09-18 15:19:49.240 954 954 E update_engine: [ERROR:delta_performer.cc(883)] The hash of the source data on disk for this operation doesn't match the expected value. This could mean that the delta update payload was targeted for another version, or that the source partition was modified after it was installed, for example, by mounting a filesystem.
09-18 15:19:49.242 954 954 E update_engine: [ERROR:delta_performer.cc(888)] Expected: sha256|hex = A5AB9CBD2E2604C0E98C704EC4F4FFFF20562517D38797F31A6A32F9B7146AF3
09-18 15:19:49.244 954 954 E update_engine: [ERROR:delta_performer.cc(891)] Calculated: sha256|hex = 9B7E9AFFFAE7F57E81A4B116E707E91E02C5A015F553F18E330A8F75B84A9826
09-18 15:19:49.247 954 954 E update_engine: [ERROR:delta_performer.cc(902)] Operation source (offset:size) in blocks: 0:1,5690:339,16383:1
09-18 15:19:49.249 954 954 E update_engine: [ERROR:partition_writer.cc(485)] source_fd != nullptr failed.
09-18 15:19:49.250 954 954 E update_engine: [ERROR:delta_performer.cc(957)] partition_writer_->PerformSourceBsdiffOperation( operation, error, buffer_.data(), buffer_.size()) failed.
09-18 15:19:49.252 954 954 E update_engine: [ERROR:delta_performer.cc(201)] Failed to perform BROTLI_BSDIFF operation 14, which is the operation 0 in partition "boot"
09-18 15:19:49.253 954 954 E update_engine: [ERROR:download_action.cc(222)] Error ErrorCode::kDownloadStateInitializationError (20) in DeltaPerformer's Write method when processing the received payload -- Terminating processing

My guess is my inactive slot "a" contains a different OS version? Pre-0705, I think.

I suspect this because several weeks ago *somehow* even though Automatic System Updates was disabled, the OS attempted to update itself (while still rooted). I came back to a "you've just gotten an update and a reboot" message, and lost root. I re-rooted, and all was well...so I thought.

I'm now very nervous about doing any of the following:

Sideload the September update via adb (there must be a good reason for the automated update to bail, right?)

Switch slots and try booting to see what's actually on there (tried this once, selecting "Turn Off" after setting "a" to active; the phone's power button would NOT power the phone on; thankfully plugging in the USB cable did; phone booted to slot "b", though)

Reflashing the A12 Magisk-patched "master root" image to slot "b", for fear of bricking the phone via A12-to-A13 bootloader compatibility.

Any help on next possible steps is appreciated. I've been rooting and manually updating Android phones for years, but man does it feel like it's getting trickier and riskier :confused: