TWRP, Updater processes ended with ERROR: 7
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.