Ok, probably you need another disk, initialize it in “disk” mode and copy backups from the original.
Can you do that?
Hmm OK you mean i have to copy all files to a disk with ext4 format? That will takes some time … 
But probably i have no other chance?
Currently the suspicion is that your current disk may have issues and if you continue you may lose data.
So it is always food to have a second disk.
Our “disk” mode uses btrfs fylesystem (not ext4) and allows adding multiple disks (usb …).
i take all files on a new disk with btrfs filesystem. after adding in storage-menu the same failure is displayed:
“Previous change
cannot find existing uuid to use”
so it cant be added as a “disk” only as a “partition”
restoring backups dont work anyway 
nextcloud error: 502 Bad Gateway - nginx/1.20.1
This will erase all data from the disk, so I assume you have all files on another disk.
If yes, when you select a disk in disk mode and push save do you get a question about removing all data, you should check that to initialize. Can you do that?
Ok - now it happened something strange: i told that I backup nextcloud data. But it seems, that restoring is not working because when I contact nextcloud by browser it comes error message 502.
But now I disconnect disk in storage menu to put switch on “disk”. My hard disk is now disconnect (says syncloud).
But now, nextcloud is working like before - so restoring backup works!!! I can see all files in nextcloud, users etc. are existing!!
Matrix/User Backup restore working too!!!
The only thing is now, that I can’t see my backups because disk is disconnected - apparently. So the list of backups is not available.
What is happened???
That means, that is it necessary to format disk to add this correct to syncloud?
So after mounting and formating I can only transfer files to the disk?
What do you say to the above listed strange problem?
cant initialize disk, error:
exit status 1: cannot snap-exec: cannot exec “/snap/users/262/hooks/storage-change”: no such file or directory
wahts the problem?
Oh, that is an error in users app, let me fix that.
As a workaround you can remove users app for now.
That means, that is it necessary to format disk to add this correct to syncloud?
Syncloud needs to format the disk before activating it unless it was already formatted by Syncloud as a disk before.
So after mounting and formating I can only transfer files to the disk?
Yes. Syncloud will mount and format (explicit warning) for you on save.
I did everything you describe on 30th march - formating disk by syncloud - transfer files - initialize with switch to “Disk” (now there is no error there") - load backups but there is following error again when i go to nextcloud page in browser:
Your data directory can be read by other users. Please change the permissions to 0770 so that the directory cannot be viewed by other users.
it dont work … i sent you logs …
Little hint: restoring nextcloud Backup unfortunately don’t work completely: writing new data is not possible…
Can you run this command:
snap run nextcloud.occ config:system:get datadirectory
Then remove Users app and reactivate disk (no need to format this time)?
Then can you run this command again:
snap run nextcloud.occ config:system:get datadirectory
Reactivate Disk seems to be frozen (after deinstall app users), in this time, nextcloud is available without permission error, but writing files is not available …
(syncloud feedback: “Current change: is in progress”)
Output of your command:
Ok I think broken Users app prevented some disk events (fix is coming) do not install Users for now.
Reinstall nextcloud please this should fix it.
Pushed the fixed Users app to the store.
Syncloud feedback after “current change: is in progress” (reactivating disk):
exit status 1: 2023-04-01 22:22:48,447 - nextcloud_occ - ERROR - occ error: Your data directory is readable by other users. Please change the permissions to 0770 so that the directory cannot be listed by other users. An unhandled exception has been thrown: Exception: Environment not properly prepared. in /snap/nextcloud/676/nextcloud/lib/private/Console/Application.php:166 Stack trace: #0 /snap/nextcloud/676/nextcloud/console.php(99): OC\Console\Application->loadCommands(Object(Symfony\Component\Console\Input\ArgvInput), Object(Symfony\Component\Console\Output\ConsoleOutput)) #1 /snap/nextcloud/676/nextcloud/occ(11): require_once(‘/snap/nextcloud…’) #2 {main} Traceback (most recent call last): File “/snap/nextcloud/676/hooks/storage-change”, line 4, in Installer().on_disk_change() File “/snap/nextcloud/676/hooks/installer.py”, line 253, in on_disk_change self.occ.run(‘config:system:delete instanceid’) File “/snap/nextcloud/676/hooks/octools.py”, line 19, in run raise e File “/snap/nextcloud/676/hooks/octools.py”, line 13, in run output = check_output(‘{0} {1}’.format(self.occ_runner_path, args), shell=True).decode().strip() File “/snap/nextcloud/current/python/usr/local/lib/python3.8/subprocess.py”, line 415, in check_output return run(*popenargs, stdout=PIPE, timeout=timeout, check=True, File “/snap/nextcloud/current/python/usr/local/lib/python3.8/subprocess.py”, line 516, in run raise CalledProcessError(retcode, process.args, subprocess.CalledProcessError: Command ‘/snap/nextcloud/current/bin/occ-runner config:system:delete instanceid’ returned non-zero exit status 1.
after this i reinstall nextcloud - load backup of nextcloud - install updated user app - load backup of user app:
same error occurs (permission 0770), now i reactivate disk again and it is “freezed” again
nextcloud is available in browser but it seems that users arent there - no login possible - not even with root (!)
update: after “freezing” - same error occurs like above - nextcloud error in browser (permission 0770)
Sorry you are making too many changes difficult to understand what breaks it.
Users backup does not really do anything as this app just changes system users and does not have its own data.
I assime your new disk contains all your data.
- Uninstall users and nextcloud (wait for finish)
- Make sure disk is activated
- Install nextcloud (wait for finish)
- Check nextcloud main user login
- Restore nextcloud backup (wait for success message)
- Check nextcloud main user login
If anything does not work during the steps do not continue and report here.
After 5. permission error occurs (0770) in browser, so no login possible
It seems, user App ist not the problem? What should I do?