Comment 36 for bug 1241811

I also have this problem and if it is the same bug I have narrowed it down to "lightdm".

I am using Mint 17 (based on Ubuntu 14.04). Mint's default login manager is "mdm" (fork of gdm). With it, usb devices are auto-mounted just fine when plugged in.

When I install lightdm and choose it as the login manager, after reboot then devices *do not auto-mount anymore*. Just as the previous poster, the dmesg output shows that the device is correctly found and attached, but not mounted. When I click on the device in Nautilus or Nemo, it will then mount just fine, but it needs this manual interaction.

If I then uninstall lightdm, choosing mdm again as the display manager, upon reboot the auto-mounting of usb devices works just fine again.

So.... it must be something in lightdm for me. A udev rule not finishing somehow triggered by lightdm? An upstart trigger involving lightdm that hangs things up? Any advice on where to look from here appreciated.