This morning I did what I expected to be a regular, monthly update to the new core, but eversince I cannot login anymore.
Both my PC (browser, also after deleting cookies) and iPhone app stopped working. Once logged in it says ‘loading data’, but then everything is stuck.
Rebooting HA server did not help.
When checking the terminal, I don’t see anything weird during boot or once booted.
Help? 
Thanks!
I’m experiencing the same issue since the update. I have rebooted, cleared cache, cleared cookies, Chrome incognito mode, Safari private…and absolutely nothing works.
Hopefully the folks at HA will chime in asap as well as resolve the issue asap.
Sorry to hear 
I am running mine as a VM, so I recovered yesterdays snapshot and am back up and running, but I will stay away from updating for a bit until things become clear.
Exact same problem here. And I had to leave for work, won’t be able to restore the backup today. 
I hope at least some workaround be found by the time I’m back home tonight…
Same issue here All tips shared by earlier user with this issue didn’t help. Needed to restore a backup.
How did you get past the open page to get the backup done?
Same issue here. I was able to restore the backup, doing the following steps:
Hopefully this works also for other users with this issue.
Thanks, but the whole issue is that homeassistant does not ‘start everything’ it seems and thus people can’t go to system-backup 
Not that is helps right now, but perhaps for next upgrade cycle.
a) never update to a .0 release
b) prowl the forums before updating (which is why I’m seeing this)
c) only update to a .3 or .4
A .0 is the cutting edge and as expected it will cause some pain.
I agree 100%…but it’s also extremely rare that an OS or core update would crash the system for what appears, way too many users. As well, the fact that the HA honchos are staying quiet on this one🤬
Anybody got any ideas? I have the same issue. Running on a Pi
So it appears to be accessible whilst it’s booting up, but then once boot up has completed, it won’t load again. So you need to get in there whilst boot up is happening and try to instigate a restore in that brief window.
Update: I was able to restore a backup using this method
My HA stuck as well. I did restore backup using CLI.
I am also getting the same issue on both 2024.12 & 2024.12.1
Stuck on the “Loading data” screen.
Thankfully, I still had access via the HA MacOS App to was able to restore from there.
Also reported there:
Several machines updated OK but my Blue is stuck on Loading Data
anyone have any luck? I been spinning for several days and cant figure out how to fix it.
Same problem here. I was able to connect my iOS app to HA by turning HA off and on and restarting the app multiple times during the boot process of HA. After a couple of tries I was able to connect and restore my backup.
I am so out of my depths on this one. I’m stuck in the same loading screen. Rebooted a bunch of times trying to get in while booting. Starting over would be a major undertaking.
Can anyone guide me thru getting files off the SD card in the Pi? Or forcing it to boot in safe mode? Can I plug a keyboard into the Pi to do that?
Same problem,
I tried to do a restore but all my recent backups are partial and are not used. The first one I have of the full type is too old. Has anyone solved it differently? Is the cause understood?
But what if I still take the contents of the tar of the partial backup and overwrite it on the config directory?
I am also having problem accessing my HA dashboard as it is stuck on “Loading data” although all my automations are still working I can’t access my dashboard, this happened when I upgraded. Does anyone know how to get this to work? I am using the blue box. Thanks!