[Nate the great]

Originally Posted by user_none

@pilotbob, This was caused by a missing import. It has been fixed for the next release.

@Nate, Similar issue. The latest 0.4.129 build has the fix. Try redownloading and installing again.

Tried it; didn't work.

C:\Program Files\calibre>calibre-debug -c "from calibre.devices.scanner import DeviceScanner; s = DeviceScanner(); s.scan(); print repr(s.devices)"
[u'usb\\root_hub&vid10de&pid026d&rev00a3', u'usb\\root_hub20&vid10de&pid026e&rev
00a3', u'usb\\vid_058f&pid_9360&rev_0100', u'usb\\vid_0b38&pid_0003&rev_0100', u
'usb\\vid_0b38&pid_0003&rev_0100&mi_00', u'usb\\vid_0b38&pid_0003&rev_0100&mi_01
', u'usb\\vid_1241&pid_1177&rev_0200', u'usb\\vid_1949&pid_0001&rev_0399']


C:\Program Files\calibre>prs500 df
Traceback (most recent call last):
File "main.py", line 337, in <module>
File "main.py", line 215, in main
File "calibre\devices\usbms\device.pyo", line 290, in open
File "calibre\devices\usbms\device.pyo", line 180, in open_windows
NameError: global name 'WINDOWS_MAIN_MEM' is not defined