Error: Unexpected exception in upload

[ph1l]

Error: Unexpected exception in upload:
Traceback (most recent call last):
  File "/usr/lib/python2.7/dist-packages/ServerBackupS3/__main__.py", line 216, in main
    backup.get_pipe()
  File "/usr/lib/python2.7/dist-packages/ServerBackupS3/S3Upload.py", line 75, in multipart_from_process
    output = process.stdout.read(CHUNK_SIZE)
MemoryError
failing backup...
Error: backup failed...
Traceback (most recent call last):
  File "/usr/bin/server-backup-s3", line 11, in <module>
    load_entry_point('ServerBackupS3==1.0.0', 'console_scripts', 'server-backup-s3')()
  File "/usr/lib/python2.7/dist-packages/ServerBackupS3/__main__.py", line 227, in main
    backup.failure()
  File "/usr/lib/python2.7/dist-packages/ServerBackupS3/BackupFilesystem.py", line 207, in failure
    self.tar_process.communicate()
  File "/usr/lib/python2.7/subprocess.py", line 471, in communicate
    stdout = _eintr_retry_call(self.stdout.read)
  File "/usr/lib/python2.7/subprocess.py", line 121, in _eintr_retry_call
    return func(*args)
ValueError: I/O operation on closed file