UrBackup 2.2.11 - Client Image Backup works, Filebackup not


I installed the urbackup server from source on ubuntu 18.04 server edition.
It runs perfectly on the server and on the client with Windows 10. But the backup within the files and folders got some problems. The image backup is working.

I run the backup server with standard values.
The error message is:

03.09.18 12:06
Cannot access path to backup: “\?\GLOBALROOT\Device\HarddiskVolumeShadowCopy40\Daten” Errorcode: 2 - Das System kann die angegebene Datei nicht finden.

03.09.18 12:06
Constructing of filelist of “AUSZUBILDENDE” failed: error - index error

03.09.18 12:06
Backup had an early error. Deleting partial backup.


Any help here? link