Maybe wait until more documentation comes out? I had the same problem except when I updated to High Sierra, not after. I had this problem on my hard drive that

Maybe wait until more documentation comes out? I had the same problem except when I updated to High Sierra, not after. I had this problem on my hard drive that "corrupted" it in a way neither Disk Utility nor Terminal accessed from the masOS recovery could fix. And before you ask, this was network recovery, so the recovery image I was using was technically not on my hard drive-- meaning I could wipe the entire drive and reinstall macOS if I had to. Found out that I'd have to wipe it, update, and restore from my backup. Easy-ish, right? No. Once I updated, I was presented with a debacle as Apple just dropped AFP support in High Sierra. Problem is, I have been using a NAS to store my Time Machine backups. THE NAS CONNECTED TO MY COMPUTER USING AFP. I had to downgrade back to Sierra, restore from the network backup, back up my system to an external hard drive, wipe the Mac's SSD, update, and restore from the backup. Only took a few weeks to get all that done :) And nope, Apple support did NOT help with this. I read an article on HN a while ago about how Apple painlessly updated an entire Mac's filesystem without any hitches, and seemed to implement HFS+ backwards compatibility better than HFS itself. Whether that's true or not, High Sierra is by no means a painless update. And don't even mention the new root bug.