[Ozman]

Well, I just tried to connect my Nexus 7 on Calibre 2.11 (multiple times) and I get the following error:

calibre, version 2.11.0
ERROR: Error: Error communicating with device

Failed to delete (u'Internal storage', u'driveinfo.calibre') with error: 2:PTP Layer error 02ff: LIBMTP_Delete_Object(): could not delete object.
2:Error 02ff: PTP: I/O error

Traceback (most recent call last):
  File "site-packages/calibre/gui2/device.py", line 87, in run
  File "site-packages/calibre/gui2/device.py", line 502, in _books
  File "site-packages/calibre/devices/mtp/driver.py", line 208, in books
  File "site-packages/calibre/devices/mtp/driver.py", line 180, in get_driveinfo
  File "site-packages/calibre/devices/mtp/driver.py", line 170, in _update_drive_info
  File "site-packages/calibre/devices/mtp/base.py", line 24, in synchronizer
  File "site-packages/calibre/devices/mtp/unix/driver.py", line 366, in put_file
  File "site-packages/calibre/devices/mtp/base.py", line 24, in synchronizer
  File "site-packages/calibre/devices/mtp/unix/driver.py", line 411, in delete_file_or_folder
DeviceError: Failed to delete (u'Internal storage', u'driveinfo.calibre') with error: 2:PTP Layer error 02ff: LIBMTP_Delete_Object(): could not delete object.
2:Error 02ff: PTP: I/O error

I even used my 'no fail cable'.

[EDIT] After several re-starts of my laptop and my Nexus 7, the connection problem disappeared.