I have the same problem. But I am able to get it to mount after plugging the phone in, going to Settings -> Developer Options and turning off USB Debuggling and turning it back on again ("Hello IT, have you tried turning it off and on again?").
----------------- agentlogic@Erebus:~$ mtp-detect Unable to open ~/.mtpz-data for reading, MTPZ disabled.libmtp version: 1.1.6 Listing raw device(s) Device 0 (VID=04e8 and PID=6860) is a Samsung Galaxy models (MTP). Found 1 device(s): Samsung: Galaxy models (MTP) (04e8:6860) @ bus 3, dev 4 Attempting to connect device(s) PTP_ERROR_IO: failed to open session, trying again after resetting USB interface LIBMTP libusb: Attempt to reset device LIBMTP PANIC: failed to open session on second attempt Unable to open raw device 0 OK. -- You received this bug notification because you are a member of Ubuntu Desktop Bugs, which is subscribed to gvfs in Ubuntu. https://bugs.launchpad.net/bugs/1314556 Title: Unable to mount Android MTP device To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/gvfs/+bug/1314556/+subscriptions -- desktop-bugs mailing list desktop-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/desktop-bugs