Restoring of Domain failed

[Greenhorn2013]

Hi,
currently i would like to restore a domain.
But restoring failed with following error:

Traceback (most recent call last):
File "/opt/psa/admin/sbin/supervisor", line 6, in ?
supervisor.main()
File "/opt/psa/admin/share/supervisor/supervisor.py", line 168, in main
pid, st = waitpid(session.extractor_pid, os.WNOHANG)
OSError: [Errno 10] No child processes

Whats going wrong? What can i do?