Android Treble enabled devices will have force encryption enabled and also DM Verity check enabled.
DM verity does not allow an Android system to boot if the system integrity has changed or in simple words, if some of the system partitions are changes such as: boot, recovery, system partition etc.
In order to flash a TWRP recovery by replacing the stock recovery you need to disable DM verity and disable force encryption.
This zip file is TWRP flashable which disables the Force Encryption on Android phone with Treble enabled.
Click on the Download button below to start the download.