Exception while start a restoration point

Reproduce the failure with ./occ backup:point:create, then trace the call chain from custom_apps/backup/lib/Service/PointService.php lines 252, 386, and 796 into lib/private/FilesMetadata/FilesMetadataManager.php:125. Check how the metadata listener handles the file written during backup initialization. Done means the command completes without the null-method exception and creates the restoration point.

It never starts creating the restore point and I'm not sure why.

This is log:

fb1686e506a5:/var/www/html$ ./occ backup:point:create
> maintenance mode: on
> initialization of the AppData
> maintenance mode: off
An unhandled exception has been thrown:
Error: Call to a member function getUID() on null in /var/www/html/lib/private/FilesMetadata/FilesMetadataManager.php:125
Stack trace:
#0 /var/www/html/lib/private/FilesMetadata/Listener/MetadataUpdate.php(59): OC\FilesMetadata\FilesMetadataManager->refreshMetadata(Object(OC\Files\Node\File))
#1 /var/www/html/lib/private/EventDispatcher/ServiceEventListener.php(86): OC\FilesMetadata\Listener\MetadataUpdate->handle(Object(OCP\Files\Events\Node\NodeWrittenEvent))
#2 /var/www/html/3rdparty/symfony/event-dispatcher/EventDispatcher.php(230): OC\EventDispatcher\ServiceEventListener->__invoke(Object(OCP\Files\Events\Node\NodeWrittenEvent), 'OCP\\Files\\Event...', Object(Symfony\Component\EventDispatcher\EventDispatcher))
#3 /var/www/html/3rdparty/symfony/event-dispatcher/EventDispatcher.php(59): Symfony\Component\EventDispatcher\EventDispatcher->callListeners(Array, 'OCP\\Files\\Event...', Object(OCP\Files\Events\Node\NodeWrittenEvent))
#4 /var/www/html/lib/private/EventDispatcher/EventDispatcher.php(94): Symfony\Component\EventDispatcher\EventDispatcher->dispatch(Object(OCP\Files\Events\Node\NodeWrittenEvent), 'OCP\\Files\\Event...')
#5 /var/www/html/lib/private/EventDispatcher/EventDispatcher.php(106): OC\EventDispatcher\EventDispatcher->dispatch('OCP\\Files\\Event...', Object(OCP\Files\Events\Node\NodeWrittenEvent))
#6 /var/www/html/lib/private/Files/Node/HookConnector.php(109): OC\EventDispatcher\EventDispatcher->dispatchTyped(Object(OCP\Files\Events\Node\NodeWrittenEvent))
#7 /var/www/html/lib/private/legacy/OC_Hook.php(105): OC\Files\Node\HookConnector->postWrite(Array)
#8 /var/www/html/lib/private/Files/View.php(1275): OC_Hook::emit('OC_Filesystem', 'post_write', Array)
#9 /var/www/html/lib/private/Files/View.php(1202): OC\Files\View->runHooks(Array, '/nxt/temporal/....', true)
#10 /var/www/html/lib/private/Files/View.php(680): OC\Files\View->basicOperation('file_put_conten...', '/admin/files/nx...', Array, '')
#11 /var/www/html/lib/private/Files/Node/Folder.php(188): OC\Files\View->file_put_contents('/admin/files/nx...', '')
#12 /var/www/html/lib/private/Files/SimpleFS/SimpleFolder.php(89): OC\Files\Node\Folder->newFile('.nobackup', '')
#13 /var/www/html/custom_apps/backup/lib/Service/PointService.php(796): OC\Files\SimpleFS\SimpleFolder->newFile('.nobackup', '')
#14 /var/www/html/custom_apps/backup/lib/Service/PointService.php(386): OCA\Backup\Service\PointService->initBackupFS()
#15 /var/www/html/custom_apps/backup/lib/Service/PointService.php(252): OCA\Backup\Service\PointService->initRestoringPoint(true)
#16 /var/www/html/custom_apps/backup/lib/Command/PointCreate.php(120): OCA\Backup\Service\PointService->create(true, '', '')
#17 /var/www/html/3rdparty/symfony/console/Command/Command.php(298): OCA\Backup\Command\PointCreate->execute(Object(Symfony\Component\Console\Input\ArgvInput), Object(Symfony\Component\Console\Output\ConsoleOutput))
#18 /var/www/html/core/Command/Base.php(177): Symfony\Component\Console\Command\Command->run(Object(Symfony\Component\Console\Input\ArgvInput), Object(Symfony\Component\Console\Output\ConsoleOutput))
#19 /var/www/html/3rdparty/symfony/console/Application.php(1040): OC\Core\Command\Base->run(Object(Symfony\Component\Console\Input\ArgvInput), Object(Symfony\Component\Console\Output\ConsoleOutput))
#20 /var/www/html/3rdparty/symfony/console/Application.php(301): Symfony\Component\Console\Application->doRunCommand(Object(OCA\Backup\Command\PointCreate), Object(Symfony\Component\Console\Input\ArgvInput), Object(Symfony\Component\Console\Output\ConsoleOutput))
#21 /var/www/html/3rdparty/symfony/console/Application.php(171): Symfony\Component\Console\Application->doRun(Object(Symfony\Component\Console\Input\ArgvInput), Object(Symfony\Component\Console\Output\ConsoleOutput))
#22 /var/www/html/lib/private/Console/Application.php(206): Symfony\Component\Console\Application->run(Object(Symfony\Component\Console\Input\ArgvInput), Object(Symfony\Component\Console\Output\ConsoleOutput))
#23 /var/www/html/console.php(100): OC\Console\Application->run()
#24 /var/www/html/occ(11): require_once('/var/www/html/c...')