TWRP, Updater processes ended with ERROR: 7 Whenever I try to flash Lineage OS with TWRP v 3.2.1-0, I'm getting

Updater processes ended with ERROR: 7
Error installing zip file '/sdcard/...n1awifi-signed.zip


When I check my recovery.log

Skipping Digest check: no Digest file found
I:Update binary zip
I:Zip does not contain SELinux file_contexts file in its root.
I:has_legacy_properties: Found legacy property match!
I:Legacy property environment initialized.
Target: samsung/lt03wifiue/lt03wifiue:5.1.1/LMY47X/P600UEUDOK1:user/release-keys
Target: samsung/lt03wifiue/lt03wifiue:5.1.1/LMY47X/P600UEUDOK1:user/release-keys
detected filesystem ext4 for /dev/block/platform/dw_mmc.0/by-name/SYSTEM
detected filesystem ext4 for /dev/block/platform/dw_mmc.0/by-name/SYSTEM
about to run program [/tmp/install/bin/backuptool.sh] with 2 args
Not backing up files from incompatible version: 14.1
run_program: child exited with status 127
about to run program [/tmp/install/bin/otasigcheck.sh] with 1 args
You have an installed system that isn't signed with this build's key, aborting...
run_program: child exited with status 124
script aborted: Can't install this package on top of incompatible data. Please try another package or run a factory reset
Can't install this package on top of incompatible data. Please try another package or run a factory reset
Updater process ended with ERROR: 7


How do I resolve this error I have validated that my TWRP and my rom (that I'm trying to flash) matches my architecture (per model number and the result of /proc/cpuinfo)
According to this post on XDA


  The reason is clear: You haven't done a factory reset. If you're coming from another rom, you can make a Titanium Backup of your apps and restore it after installing cm11. [...] Either way, you need to do a factory reset/full wipe. You will lose your apps, data, pretty much everything. Make a backup first, do the wipe, then it will install.