TWRP: Failed to mount '/data' When I try to install a ROM with TWRP, I get

Could not mount /data and unable to find crypto footer.
Failed to mount '/data' (Invalid argument)
Unable to recreate /data/media folder.
Updating partition details...
Failed to mount '/data' (Invalid argument)
...done
Unable to mount storage
Failed to mount '/data' (Invalid argument)
Full SELinux support is present
Unable to mount /data/media/TWRP/.twrps


Then when I try to "Factory Reset" under TWRP Wipe, I get

/sbin/e2fsck -fp /dev/block/sda18 process ended with ERROR: 8
Unable to repair Data.
Failed to mount '/data' (Invalid argument)
Error changing file systems
Repairing Data using e2fsck...


I am using a Samsung Galaxy S7.
What you need to do is remove Crypto on Data

To do that, in TWRP


Settings
Format Data
Type "yes"
Done