Traceback (most recent call last):
  File "/usr/share/usb-creator/install.py", line 156, in <module>
    main(source, target, persist)
  File "/usr/share/usb-creator/install.py", line 134, in main
    popen(['dd', 'if=/dev/zero', 'bs=%sM', 'of=%s/casper-rw' % target, 'count=1' % persist])
TypeError: not all arguments converted during string formatting