Can't start Backup manually

Hey, I'm currently have some Problems with the Backups overall and to troubleshoot it I want to start the Backup manually but I'm getting following Error:

sudo -u www-data php /var/www/nextcloud/occ backup:point:create

> maintenance mode: on
> initialization of the AppData
> maintenance mode: off
An unhandled exception has been thrown:
TypeError: OC\Files\View::basicOperation(): Argument #2 ($path) must be of type string, null given, called in /var/www/nextcloud/lib/private/Files/View.php on line 528 and defined in /var/www/nextcloud/lib/private/Files/View.php:1128
Stack trace:
#0 /var/www/nextcloud/lib/private/Files/View.php(528): OC\Files\View->basicOperation()
#1 /var/www/nextcloud/lib/private/Files/Filesystem.php(545): OC\Files\View->file_exists()
#2 /var/www/nextcloud/apps/files_versions/lib/Storage.php(190): OC\Files\Filesystem::file_exists()
#3 /var/www/nextcloud/apps/files_versions/lib/Listener/FileEventsListener.php(196): OCA\Files_Versions\Storage::store()
#4 /var/www/nextcloud/apps/files_versions/lib/Listener/FileEventsListener.php(102): OCA\Files_Versions\Listener\FileEventsListener->write_hook()
#5 /var/www/nextcloud/lib/private/EventDispatcher/ServiceEventListener.php(86): OCA\Files_Versions\Listener\FileEventsListener->handle()
#6 /var/www/nextcloud/3rdparty/symfony/event-dispatcher/EventDispatcher.php(230): OC\EventDispatcher\ServiceEventListener->__invoke()
#7 /var/www/nextcloud/3rdparty/symfony/event-dispatcher/EventDispatcher.php(59): Symfony\Component\EventDispatcher\EventDispatcher->callListeners()
#8 /var/www/nextcloud/lib/private/EventDispatcher/EventDispatcher.php(94): Symfony\Component\EventDispatcher\EventDispatcher->dispatch()
#9 /var/www/nextcloud/lib/private/EventDispatcher/EventDispatcher.php(106): OC\EventDispatcher\EventDispatcher->dispatch()
#10 /var/www/nextcloud/lib/private/Files/Node/HookConnector.php(100): OC\EventDispatcher\EventDispatcher->dispatchTyped()
#11 /var/www/nextcloud/lib/private/legacy/OC_Hook.php(105): OC\Files\Node\HookConnector->write()
#12 /var/www/nextcloud/lib/private/Files/View.php(1275): OC_Hook::emit()
#13 /var/www/nextcloud/lib/private/Files/View.php(1144): OC\Files\View->runHooks()
#14 /var/www/nextcloud/lib/private/Files/View.php(680): OC\Files\View->basicOperation()
#15 /var/www/nextcloud/lib/private/Files/Node/Folder.php(188): OC\Files\View->file_put_contents()
#16 /var/www/nextcloud/lib/private/Files/SimpleFS/SimpleFolder.php(89): OC\Files\Node\Folder->newFile()
#17 /var/www/nextcloud/apps/backup/lib/Service/PointService.php(796): OC\Files\SimpleFS\SimpleFolder->newFile()
#18 /var/www/nextcloud/apps/backup/lib/Service/PointService.php(386): OCA\Backup\Service\PointService->initBackupFS()
#19 /var/www/nextcloud/apps/backup/lib/Service/PointService.php(252): OCA\Backup\Service\PointService->initRestoringPoint()
#20 /var/www/nextcloud/apps/backup/lib/Command/PointCreate.php(120): OCA\Backup\Service\PointService->create()
#21 /var/www/nextcloud/3rdparty/symfony/console/Command/Command.php(298): OCA\Backup\Command\PointCreate->execute()
#22 /var/www/nextcloud/core/Command/Base.php(177): Symfony\Component\Console\Command\Command->run()
#23 /var/www/nextcloud/3rdparty/symfony/console/Application.php(1040): OC\Core\Command\Base->run()
#24 /var/www/nextcloud/3rdparty/symfony/console/Application.php(301): Symfony\Component\Console\Application->doRunCommand()
#25 /var/www/nextcloud/3rdparty/symfony/console/Application.php(171): Symfony\Component\Console\Application->doRun()
#26 /var/www/nextcloud/lib/private/Console/Application.php(213): Symfony\Component\Console\Application->run()
#27 /var/www/nextcloud/console.php(100): OC\Console\Application->run()
#28 /var/www/nextcloud/occ(11): require_once('...')

I'm trying to find help to this Problem now for 2 hours but without any succes unfortunateley.
I'm running a NextcloudPi instance on a Proxmox lxc, everything is up to date.

Start with apps/backup/lib/Service/PointService.php at the initBackupFS and create call sites, then follow the files_versions Storage and FileEventsListener frames in the stack trace. Reproduce occ backup:point:create and determine why the file operation receives a null path; done means the command completes without the TypeError.