When I got up this morning I noticed that my system was not responding. I tried to open the web UI and got an error 500 and could not open anything. I disconnected the power on the hub to reboot and when it came back up it is going through the new hub setup process.
Everything has been been working great up to this point. Please tell me I haven't lost everything.
Contact Support immediately.
How is your backup situation? I suspect Support will ask you to restore your most recent backup.
But talk to them first.. @bobbyD is a magician sometimes. 
Obviously I don't know your specifics..
generically, your backup, whatever vintage, will get you back to that condition, with caveats...
Your ZWave Controller (your Hubitat Hub) has a DB of Joined devices.. and any mismatch between it and the backup will end up being the focus of your recovery, in my opinion.
All of the above make the ZStick's DB diverge from the Hub DB you're going to be reverting to.
Hubitat will clean-up 'orphan' (deleted) devices, but how it handles Adds (Devices known to the stick, invisible within the Hub's DB) is not clear at all.
I just got the error 500. Anything you want / I can do before restoring from a backup?
I was at work, saw that many people were having the issue, so when I came home I decided the first thing I needed was a new backup. The hub was working / lights came on when I got home.
When I woke my laptop, there were 2 Chrome windows still open to Hubitat from last night. I used one of the tabs to go to backup, the page loaded, I hit backup, and it just spun for a while and said "waiting" and never downloaded a file. After a while I gave up and tried to go to dashboard, then the error came up. It's possible looking back I didn't give it long enough to finish... but I do backups often and this one at least felt a lot longer.
Actually, while it says "error 500" on my screen, my motion lights are still working... I haven't done anything since the screen popped up.
try a completely different browser?
I have three hubs upgraded yesterday and the 3rd gave me a heart attack with err 500 but I just opened a new tab and browsed to it again. It worked and I just closed the err 500 tab as quick as I could 
LOL. I have the impression I might be fine as automations are still going. Just wondering if there is any data they can get from me to help with the issue before I start mucking around.
Just went back to the page, in order to restart the hub, and noticed this:
Going to start playing with it and see what I've lost, if anything.
System is completely restored with all 227 devices and apps functioning like nothing even happened. The backup and restore functions worked well. This is something I never could have done with my Iris ecosystem.
Well done Hubitat team and thanks @bobbyD for your help!
Totally agree. I’ve done a soft reset on my system few times. The process is so easy and fast.
@bobbyD add me to the list of people experiencing database corruption and reboot to "wiped" hub, rolling back to 2.1.1.114 and restoring from backup
I'm already a proud member of that list.
Download the Hubitat app
