• You want fastboot up and running. Don’t even attempt any of this if you don’t.
  • Unlocked Bootloader and Critical Partitions

Unlocking the Bootloader

  • Bootloader can be unlocked via fastboot flashing unlock THIS WILL WIPE YOUR DATA
  • It is important you also fastboot flashing unlock_critical. This allows updating firmware partitions through fastboot. Failure to do so has caused issues for users attempting to revert to stock.

Working with A/B Partitioning

The two boot partitions on this device, named boot_a and boot_b respectively, are not your “traditional” boot partitions. Both of these partitions contain a kernel and ramdisk like you are probably used to. The difference is that the ramdisk is now your recovery. This device uses a “system-as-root” layout, with which the system partition now contains what would have been the ramdisk.

The A/B partitioning scheme can be quite confusing to users. There are actually two copies of many of the partitions


The concept of ‘slots’ comes into play to determine whether you are booting ‘slot A’ or ‘slot B’. We can determine which slot is ‘active’ or marked for booting via adb:

adb shell getprop ro.boot.slot_suffix

and via fastboot:

fastboot getvar current-slot

At any time we can switch to the next inactive slot using:

fastboot set_active other, or we can use:

fastboot set_active [a,b], to manually switch to a specified slot.

The slots are designed to enable seamless system upgrades. Android can install an update to the inactive slot while it is still running. Once the update is completed, and optimized, Android will tell the system to switch to the slot that was upgraded. This means, unless tampered with, one slot will always be one version behind.

A/B Partitioning not only reduces ‘first boot’ time by performing dexopt before rebooting, it also prevents boot failures from failed updates. If Android fails to boot it will switch back to the previous slot so that the next reboot will be back on the current, working, slot.

Installing LineageOS

You will need to flash TWRP, the latest can be found here: Flash it to the boot partition with fastboot.

invisiblek’s Lineage builds can be found here:

This is flashed the normal way through TWRP. More info and instructions here:

Common Issues

Fingerprint Scanner Stopped Working

Chances are you have a firmware mismatch. Typically checking your build.prop for the build version and flashing the matching firmware package will fix this.

Firmware packages here:

If you move data between devices or change encryption. You may end up with a nonworking fingerprint scanner after restoring data from a twrp backup. If this occurs, you can flush the recorded fingerprint data by deleting /data/system/users/0/fpdata and /data/system/users/0/settings_fingerprint.xml. You should now be able to re-enroll your fingerprints.

I Cant Boot After Restoring a Backup

This is usually caused by the fact that you had to flash TWRP in order to get in to TWRP. Therefore, when you did your backup, it actually backed up the TWRP install instead of your ROM’s boot.img. The kernel included with TWRP cannot boot Android.

I recommend swapping slots before flashing and booting into TWRP. This will flash twrp onto your older, non-booting, slot. fastboot set_active other will switch slots for you.

Once you get to TWRP, go to the reboot menu, change to the other (original) slot, and finally perform your backup. Make sure you always decrypt your data, in TWRP, before backing up. It’s unlikely backing up the encrypted FDE data is viable to restore. (Tinfoilers can always encrypt the twrp backup that is generated with the check of a box)

No Touch in TWRP

Some day you may end up with a firmware that doesn’t play well with twrp. Either no touch screen, or no data decryption.

One quick way to flash a zip in this situation is to put the device in sideload mode via an adb command: adb shell twrp sideload then flash your zip using adb sideload:

adb sideload

Broken Crypto

If you get an error about ExtractTarFork() its plausible that you have a problem with crypto. It is likely that what is currently on your device is unhappy with how things were backed up.

The best way I’ve found to fix this is to perform a data wipe in fastboot via fastboot -w, then boot into your ROM (with clean data), go through the setup wizard and set a lockscreen password/pin (preferably matching what you had before), then reboot into twrp and restoring your data.

Firmware between N and O are finicky when it comes to crypto. I’m not even sure I’ve even wrapped my head around all the ins and outs of Oreo’s crypto yet. If you’re backing up/restoring with O firmware, as of (2017-11-22) you’re on your own.


Flashing magisk after a rom is a bit of a problem. The official magisk zip ends up installing it to the currently booted slot. Typically though, you’d want to be installing it to the inactive slot after flashing a ROM zip (and thus switching to the slot the rom was installed to).

I’ve made a hacked magisk zip that forces the flash to go to the opposite slot that you are booted to in order to alleviate this headache:

Flash this after flashing your rom while you’re still in TWRP.

Removing the Red Verity Warning

The red verity message that appears on modified systems and requires you to hit the power button to boot can be cleared by fastboot flashing this boot.img:

That image will reboot over and over again (you’ll never get anywhere) but when it does, it’ll clear out that annoying red error. After flashing it, boot normally once. You will still get the red error but it will be cleared at the next reboot.