oneplus 3T lineageOS 17.1 androd 10 with nethunter 2020.2 Oneplus3 Any Ten

and

oneplus 3T Oxygen 9.02 pie with with nethunter 2020.2 Oneplus3 Any Pie

in twrp both gives the same error when installing it

"TWRP error mount system con rw!"


unlocking your device and updating it to stock AOSP or LineageOS (CM). (Check point 2.0 for supported roms)
installing Team Win Recovery Project as a custom recovery.
installing Magisk to root the device
disabling force encryption may be required if TWRP cannot access the data partition
Once you have a custom recovery, all that remains is to flash the NetHunter installer zip file onto your Android device.