I noticed all my devices in Home Assistant were down so I went to access my C8 hub web interface and I got error "Corrupt Database Found." I haven't made any changes to the C8 in days and was working fine 2 days ago. I followed the soft reset instructions but when its booting it stays on "60% - Starting UPNP" for hours. I tried to get into safe mode... It reboots and I see the normal Hub C8 webpage but nothing works and is VERY slow and eventually get the DB error.
Booting into Safe Mode disables everything so you can remove a misbehaving device or integration then reboot in normal mode, so nothing working in Safe Mode is expected behavior. Now with the hub accessible, can you identify which device or app is causing the problem? Past logs and/or Devices/Apps Stats tabs should help isolate the problem.
My post that you quoted mentions that nothing works still even in safe mode. Things are SUPER slow and not responsive when I click on anything on the webpage. I just tried safe mode again and wont go into it. Just says hub is rebooting
Nothing was changed in the last 7+ days in terms of devices being added, integrations, etc. Just stopped working out of no where.
Even though you may not have changed anything physically, devices and integrations make changes to your hub, on your behalf every second, or less. If one starts misbehaving, the result is what you describe.
Try running the soft reset again, if that doesn't work, you may need to create a warranty case by visiting the following page: Warranty – Hubitat Support
I've attempted a soft reset 5+ times. I was able to download a backup. Should I try a factory reset? If I do that do I have to add all my Z-wave, zigbee devices manually back into Hubitat again?
Yes, unless you have a cloud backup, not a local backup.
If the Soft Reset wasn't able to resolve the database issue, a full reset is unlikely to help either. You may just be dealing with a hardware malfunction.
Are you a Hub Protect subscriber? That is the only way to enable cloud backups. If you are not a subscriber, then you don't have a cloud backup. If you send me your hub ID in a private message, I could check to see if the hub is connected to the cloud, and if it is, I should be able to retrieve the engineering logs that might give us clues about what went wrong.