[OnePlus 8T ROMs, Kernels, Recoveries, & Other Deve] IAAxl:
Thank you LuK1337! You've saved almost every OnePlus device from their terrible stock system, you're the true hero! (Please forgive me OOS lovers, no offense but personally I really don't like OOS...)

The release of LOS 20 makes me very excited and super nervous... Because last time when I tried to upgrade from LOS 18 to 19 without proper backup (my bad, I have to admit), I bricked my phone and had no other choice but to erase all data and do a fresh install...

I'm far from an Android pro. But please let me share my understanding of the correct upgrade steps here, as the information on official LOS wiki is very fragmented. I wanna know if I've did anything wrong (or if I'm going to do anything wrong). PLEASE DO CORRECT ME, I really need help from every reader. I hope my tragedy won't happen again on any other regular users.

Goals:​

1. Do a proper full backup.

2. Upgrade LOS from 19.1 to 20.0 with Magisk and MindTheGapps installed, without losing data.

3. [Optional] Restore LOS 19.1 backup from super bricked state (e.g. can't enter fastboot after upgrade firmware, which was my state).

1. Do a proper full backup.​

Edit: I found how to pass root access to work profile and neo backup app can handle it now (after it's also installed in work profile). My bad, sorry neo backup, you're a great app!

Since the built-in SeedVault can't handle apps that "opt-out of the system backup", and other root based per-app backup software (e.g. neo backup) can't handle data inside work profile, partition mirror backup (aka NAND backup) seems to be the final reliable option.

But there isn't any official stable recovery for kebab on Android 13 firmware (currently there's only an unofficial pre-release OrangeFox recovery available), so manual ADB operation seems to be necessary.

After googling I found this article "https://eskerahn.dk/?p=4633" seems promising (not too old, not too complex).

I tried myself and it seems to work.

1.a) Reboot to LOS recovery.

1.b) Advanced - Enable ADB.

1.c) Launch ADB shell on PC and run commands as shown below

Spoiler content hidden.

1.d) Quit ADB shell and run ADB pull on PC to pull partitions' raw data. Make sure you have more stroage space on PC than your phone's total storage capacity, as the data is raw and uncompressed. And be sure to use a reliable USB cable.

Spoiler content hidden.

1.e) [Optional] Compress the pulled files to save storage space.

2. Upgrade LOS from 19.1 to 20.0 with Magisk and MindTheGapps installed, without losing data.​

I haven't executed any of these steps below as I'm waiting the next LOS 20 release. Can't wait anymore! Thank Shmi117 for the sharing, you gave me the courage to proceed!

The following steps are the result of summarizing multiple wiki articles.

They should work but I'm not sure. I've already followed these steps and had a successful upgrade!

If you've already went through the upgrade please help check if there's any error or missing stuff, thank you!

2.a) Read every article about this device on LOS wiki and understand the risks. (https://wiki.lineageos.org/devices/kebab/)

2.b) Reboot to fastboot and update firmware to OOS 13 version. (https://wiki.lineageos.org/devices/kebab/fw_update) (BTW last time, I can't re-enter fastboot after this step. No idea what's wrong... Please correct me if you find any mistake!)

2.c) Stay in fastboot, flash LOS 20.0 recovery img for BOTH SOLTS. (Shmi117 have already discovered that LOS 19.1 recovery is still bootable after the firmware upgrade. But I still prefer less risks so I executed this step.)

2.d) Reboot to recovery (should be shown as LOS 20.0), flash LOS 20.0 system zip package.

2.e) If you have MindTheGapps installed, reboot to recovery NOW (you should notice the active slot has changed) and flash the Android 13 version MindTheGapps.

2.f) If you have Magisk installed, reboot to fastboot NOW and flash the patched LOS 20 boot img. (You can get it before this upgrade or with another magisk patched device.)

2.g) Finally. Reboot to system and wish yourself good luck. Hopefully it will boot normally and enter the exciting LOS 20.0 system with all your good old data.

2.f) Check Magisk modules, APP permissions, Android settings, launcher icons and so on...

3. [Optional] Restore LOS 19.1 backup from super bricked state (e.g. can't enter fastboot after upgrade firmware, which was my state).​

I haven't tested these steps yet.

They should work but I'm not sure... Maybe some permission issues are waiting ahead...

Please correct me if you find any error or mistake!

Since last time, I wasn't able to enter fastboot after firmware upgrade... Let's start with a 9008 bricked device.

3.a) Use MsmTools to unbrick your device. This will restore your device to an old stock system and lock your bootloader. (See "https://xdaforums.com/t/op8t-oos-kb...l-to-restore-your-device-to-oxygenos.4180837/" and "https://xdaforums.com/t/op8t-oos-tmo-kb09cb-unbrick-tool-to-restore-your-device-to-oxygenos.4180981/".)

3.b) Update your stock rom to the latest OOS 12 (because you're going to restore a backup from LOS 19.1, which is based on OOS 12 firmware.)

3.c) Unlock your bootloader and flash LOS 19.1 recovery.

3.d) Reboot to LOS 19.1 recovery, enable ADB and connect to PC.

3.e) [Not sure] Check the current slot. Make sure the current slot is the same as when the backup is pulled. I don't know where the current slot info is stored. I'm not sure what will happen if this is mismatched.

3.f) Run adb push commands on PC.

Spoiler content hidden.

3.g) Power off your device, pray for peace, and boot it up. Hopefully you'll get everything back.

I'm not a native English speaker. I sincerely ask everyone to point out any mistake I've made, for the benefit of me and other noobs like me. Thanks a lot!