OTA Updates and Magisk

[sparxooo]

Thank you Daveio for the rooting guide!

Something I have noticed - OTA updates fail once the device is rooted. I wanted to root early (to prevent Loop from disabling it on cancelling the data sub, although I have since read they are quite adament the hardware is separate and not dependent upon it).

I would imagine (and early testing, before I mixed up my images and accidentally overwrote the non-magisk ones, seems to suggest), that restoring the original init_boot_a/b, let the OTA update proceed, then re-install Magisk to the inactive slot before rebooting, seems to work. I think you may also be able to uninstall Magisk from the app, then reinstall (into the inactive slot, before rebooting!) which would have the same effect, but I haven't tested this.

Unless a "Full" OTA update appears in the meantime, I'm going to have to wait until I'm home before fully restoring with my, thankfully, full set of partition backup images.

Another use-case I've got for this device is taking on holiday - the last hotel we stayed at had a very annoying WiFi portal which prevented even their own smart TVs from signing in, let alone other smart tech that wasn't the latest and greatest - so even without a data plan, sharing the wifi network alone may solve issues!

Edit:

This is the partial Logcat for the OTA update failing:

01-31 21:30:02.290 1117 1117 I update_engine: [INFO:partition_writer.cc(177)] Applying 8 operations to partition "init_boot"
01-31 21:30:02.290 1402 1710 D InetDiagMessage: Destroyed 0 sockets, proto=IPPROTO_TCP, family=AF_INET, states=14
01-31 21:30:02.292 1402 1710 D InetDiagMessage: Destroyed 0 sockets, proto=IPPROTO_TCP, family=AF_INET6, states=14
01-31 21:30:02.292 1402 1710 D InetDiagMessage: Destroyed live tcp sockets for uids={10052} in 2ms
01-31 21:30:02.325 1117 1117 E update_engine: [ERROR:fec_file_descriptor.cc(32)] No ECC data in the passed file
01-31 21:30:02.325 1117 1117 E update_engine: [ERROR:verified_source_fd.cc(56)] Unable to open ECC source partition /dev/block/by-name/init_boot_b: Invalid argument (22)
01-31 21:30:02.326 1117 1117 E update_engine: [ERROR:partition_writer.cc(316)] 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.
01-31 21:30:02.326 1117 1117 E update_engine: [ERROR:partition_writer.cc(321)] Expected: sha256|hex = BB611F9ABF754A35ADBBD25BAC6FC358D1144D65C041117408908F0ADEBE9B43

[wu21-web]

Google’s OTA update engine verifies the hash of the init_boot partition (where Magisk is patched) against the factory/untouched SHA256 value. That is the rooot cause.The No ECC data error is a secondary symptom, and the OTA can’t validate the modified partition, so it aborts the update.
You have. to first restock the init_boot partition using Magisk's backup.
The OTA installs to the inactive slot (e.g., if you’re on slot A, it installs to slot B). Rebooting now would boot the unrooted updated slot. Then you need to re-root the inactive slot first.
After what you have to re-root the inactive slot before the device reboots.
REMINDER: DO NOT REBOOT AFTER OTA DOWNLOADS/INSTALLS
good luck on rooting!

[sparxooo]

Luckily I had kept a copy of the partitions from when I first rooted, so replaced the init_boot with the original, let it fully OTA update and then re-rooted it.

I missed the renewal window to cancel the subscription so have another month of unlimited data to mess with - it's been with me on a few long car journeys and quite impressed with the 3 network. £25 seems steep but when you consider I got the device for a quid! £295 now on the website.

Thanks for your reply wu21! The last time I meddled with re-flashing android devices was my old ZTE Blade, and I've just looked that up again and now I feel old.