"Error is occured during scheduled backup"

[flupke]

got dozens of emails from the server today, with the title "Error is occured during scheduled backup", email body contains following details:

Following error is occured during scheduled backup process, any hints?

----- email content

Error in UploadToRepositoryState.doActivityRunner()
Traceback (most recent call last):
File "/usr/local/psa/admin/share/agent_runner/agent_runner.py", line 98, in doActivityRunner
newState = self.doActivity()
File "/usr/local/psa/admin/share/agent_runner/agent_runner.py", line 428, in doActivity
shutil.copyfileobj(localfh, remotefh)
File "/usr/lib/python2.4/shutil.py", line 25, in copyfileobj
fdst.write(buf)
File "/usr/local/psa/admin/lib/python/ftputil/ftp_file.py", line 196, in write
self._fo.write(data)
File "/usr/lib/python2.4/socket.py", line 256, in write
self.flush()
File "/usr/lib/python2.4/socket.py", line 243, in flush
self._sock.sendall(buffer)
error: (32, 'Broken pipe')