Unable to flash any ROM using TWRP

[vicky_ag]

I am trying to install custom roms on Moto G3. But whatever ROM I try, I keep getting:

detected filesystem ext4 for /dev/block/bootdevice/by-name/system

Can't install this package on top of incompatible data. Please try another package or run a factory reset.

 

[hossman]

You need to wipe first.
Don't forget to backup