The filename was:

Hauptstädte.pps

Full error as follows:

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
    An unexpected error has occurred.
  Please report the following lines to:
   s3tools-bugs@lists.sourceforge.net
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Problem: UnicodeDecodeError: 'ascii' codec can't decode byte 0xc3 in position 33: ordinal not in range(128)
S3cmd:   1.1.0-beta3
Traceback (most recent call last):
  File "/usr/bin/s3cmd", line 1800, in <module>
    main()
  File "/usr/bin/s3cmd", line 1741, in main
    cmd_func(args)
  File "/usr/bin/s3cmd", line 967, in cmd_sync
    return cmd_sync_remote2local(args)
  File "/usr/bin/s3cmd", line 707, in cmd_sync_remote2local
    output(u"download: %s -> %s" % (remote_list[key]['object_uri_str'], remote_list[key]['local_filename']))
UnicodeDecodeError: 'ascii' codec can't decode byte 0xc3 in position 33: ordinal not in range(128)
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
    An unexpected error has occurred.
    Please report the above lines to:
   s3tools-bugs@lists.sourceforge.net
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!