Deleting file on federation share not possible

NC version 20.0.4.1 on both machines
both Raspberry Pi4
Host of the share has ncp standard image buster installed and updated
The clinet NC has NCP installed via curl installer on a Buster64 Raspberry OS

The problem i faced:

I have a folder on the host machine shared by user a to the client machine user b via federation, the settings of the share allow deleting files, but it was not possible to delete a file that i just uploaded there.

The nc log says this:

 Fatal   webdav   vor 3 Stunden

OC\User\NoUserException: Backends provided no user object

<<closure>>

OC\Files\Node\Root->getUserFolder("user@cloud.tld/")

/var/www/nextcloud/lib/private/Files/Node/LazyFolder.php - line 66:

call_user_func_array([ OC\Files\N ... "], [ "user@cloud.tld/"])

/var/www/nextcloud/lib/private/Files/Node/LazyRoot.php - line 41:

OC\Files\Node\LazyFolder->__call("getUserFolder", [ "user@cloud.tld/"])

/var/www/nextcloud/apps/files_trashbin/lib/Storage.php - line 141:

OC\Files\Node\LazyRoot->getUserFolder("user@cloud.tld/")

/var/www/nextcloud/apps/files_trashbin/lib/Storage.php - line 181:

OCA\Files_Trashbin\Storage->shouldMoveToTrash("IMG_20210103_203542.png")

/var/www/nextcloud/apps/files_trashbin/lib/Storage.php - line 99:

OCA\Files_Trashbin\Storage->doDelete("IMG_20210103_203542.png", "unlink")

/var/www/nextcloud/apps/ransomware_protection/lib/StorageWrapper.php - line 263:

OCA\Files_Trashbin\Storage->unlink("IMG_20210103_203542.png")

/var/www/nextcloud/lib/private/Files/View.php - line 1167:

OCA\RansomwareProtection\StorageWrapper->unlink("IMG_20210103_203542.png")

/var/www/nextcloud/lib/private/Files/View.php - line 724:

OC\Files\View->basicOperation("unlink", "/cloudserver s ... g", [ "delete"])

/var/www/nextcloud/apps/dav/lib/Connector/Sabre/File.php - line 466:

OC\Files\View->unlink("/cloudserver s ... g")

/var/www/nextcloud/3rdparty/sabre/dav/lib/DAV/Tree.php - line 183:

OCA\DAV\Connector\Sabre\File->delete()

/var/www/nextcloud/3rdparty/sabre/dav/lib/DAV/CorePlugin.php - line 295:

Sabre\DAV\Tree->delete("files/UserB/ ... g")

/var/www/nextcloud/3rdparty/sabre/event/lib/WildcardEmitterTrait.php - line 89:

Sabre\DAV\CorePlugin->httpDelete(Sabre\HTTP\Request {}, Sabre\HTTP\Response {})

/var/www/nextcloud/3rdparty/sabre/dav/lib/DAV/Server.php - line 474:

Sabre\DAV\Server->emit("method:DELETE", [ Sabre\HTTP ... }])

/var/www/nextcloud/3rdparty/sabre/dav/lib/DAV/Server.php - line 251:

Sabre\DAV\Server->invokeMethod(Sabre\HTTP\Request {}, Sabre\HTTP\Response {})

/var/www/nextcloud/3rdparty/sabre/dav/lib/DAV/Server.php - line 319:

Sabre\DAV\Server->start()

/var/www/nextcloud/apps/dav/lib/Server.php - line 332:

Sabre\DAV\Server->exec()

/var/www/nextcloud/apps/dav/appinfo/v2/remote.php - line 35:

OCA\DAV\Server->exec()

/var/www/nextcloud/remote.php - line 167:

require_once("/var/www/ne ... p")

Deleting the file on the host server by user a was possible