Here,Hello friends, I'm in ViperOS Viper-z2_plus-20181118-v5.0-OFFICIAL which is No Treble. I want to update to Android 9, flashing ViperOS v6.3, someone can tell me a brief tutorial to do it, since I did the following thing:
1. Wipe data, system, dalvik and cache
2. flash factory to vendor of this thread: https://forum.xda-developers.com/lenovo-zuk-z2/how-to/z2plus-treble-roms-flashing-reverting-t3778287
3. With the official twrp flash image (selecting recovery) recovery treble of this thread: https://forum.xda-developers.com/lenovo-zuk-z2/how-to/z2plus-treble-roms-flashing-reverting- t3778287
3. Flash rom and at the end I get this error: updater process ended with error 7. and above this puts E2001: failed to update vendor image
First you need a vendor mounted as factory.
Find required files here https://forum.xda-developers.com/lenovo-zuk-z2/how-to/z2plus-treble-roms-flashing-reverting-t3778287
Flash latest twrp from above thread and you're good to go!