I'm also seeing these same errors on my 16.04.1LTS 64bit install with kernel 4.4.0-34-generic #53-Ubuntu SMP

Aug 13 07:35:12 localhost colord[2417]: (colord:2417): Cd-WARNING **: failed to get session [pid 25642]: No such device or address
Aug 13 07:41:15 localhost colord[2417]: (colord:2417): Cd-WARNING **: failed to get session [pid 25880]: No such device or address
Aug 13 07:41:15 localhost colord[2417]: (colord:2417): Cd-WARNING **: failed to get session [pid 25880]: No such device or address
Aug 13 08:04:40 localhost colord[2417]: (colord:2417): Cd-WARNING **: failed to get session [pid 27636]: No such device or address
Aug 13 08:04:40 localhost colord[2417]: (colord:2417): Cd-WARNING **: failed to get session [pid 27636]: No such device or address
Aug 13 08:10:42 localhost colord[2417]: (colord:2417): Cd-WARNING **: failed to get session [pid 27919]: No such device or address
Aug 13 08:10:42 localhost colord[2417]: (colord:2417): Cd-WARNING **: failed to get session [pid 27919]: No such device or address
Aug 13 08:13:26 localhost colord-sane: io/hpmud/musb.c 2095: Invalid usb_open: Permission denied
Aug 13 08:13:26 localhost colord-sane: io/hpmud/pp.c 627: unable to read device-id ret=-1
Aug 13 08:16:43 localhost colord[2417]: (colord:2417): Cd-WARNING **: failed to get session [pid 28182]: No such device or address
Aug 13 08:16:43 localhost colord[2417]: (colord:2417): Cd-WARNING **: failed to get session [pid 28182]: No such device or address
Aug 13 09:03:00 localhost colord[2417]: (colord:2417): Cd-WARNING **: failed to get session [pid 30397]: No such device or address
Aug 13 09:03:01 localhost colord[2417]: (colord:2417): Cd-WARNING **: failed to get session [pid 30397]: No such device or address
Aug 13 10:01:20 localhost colord[2417]: (colord:2417): Cd-WARNING **: failed to get session [pid 1284]: No such device or address
Aug 13 10:01:21 localhost colord[2417]: (colord:2417): Cd-WARNING **: failed to get session [pid 1284]: No such device or address
Aug 13 10:07:22 localhost colord[2417]: (colord:2417): Cd-WARNING **: failed to get session [pid 1514]: No such device or address
Aug 13 10:07:22 localhost colord[2417]: (colord:2417): Cd-WARNING **: failed to get session [pid 1514]: No such device or address
Aug 13 10:13:23 localhost colord[2417]: (colord:2417): Cd-WARNING **: failed to get session [pid 1760]: No such device or address
Aug 13 10:13:23 localhost colord[2417]: (colord:2417): Cd-WARNING **: failed to get session [pid 1760]: No such device or address
Aug 13 10:19:25 localhost colord[2417]: (colord:2417): Cd-WARNING **: failed to get session [pid 2003]: No such device or address
Aug 13 10:19:25 localhost colord[2417]: (colord:2417): Cd-WARNING **: failed to get session [pid 2003]: No such device or address
Aug 13 10:25:26 localhost colord[2417]: (colord:2417): Cd-WARNING **: failed to get session [pid 2264]: No such device or address
Aug 13 10:25:26 localhost colord[2417]: (colord:2417): Cd-WARNING **: failed to get session [pid 2264]: No such device or address
Aug 13 10:59:38 localhost colord[2417]: (colord:2417): Cd-WARNING **: failed to get session [pid 3780]: No such device or address
Aug 13 10:59:38 localhost colord[2417]: (colord:2417): Cd-WARNING **: failed to get session [pid 3780]: No such device or address
Aug 13 11:05:39 localhost colord[2417]: (colord:2417): Cd-WARNING **: failed to get session [pid 4042]: No such device or address
Aug 13 11:05:39 localhost colord[2417]: (colord:2417): Cd-WARNING **: failed to get session [pid 4042]: No such device or address
Aug 13 11:11:42 localhost colord[2417]: (colord:2417): Cd-WARNING **: failed to get session [pid 4353]: No such device or address
Aug 13 11:11:42 localhost colord[2417]: (colord:2417): Cd-WARNING **: failed to get session [pid 4353]: No such device or address
Aug 13 11:17:45 localhost colord[2417]: (colord:2417): Cd-WARNING **: failed to get session [pid 10259]: No such device or address
Aug 13 11:17:45 localhost colord[2417]: (colord:2417): Cd-WARNING **: failed to get session [pid 10259]: No such device or address
Aug 13 11:23:49 localhost colord[2417]: (colord:2417): Cd-WARNING **: failed to get session [pid 10586]: No such device or address
Aug 13 11:23:49 localhost colord[2417]: (colord:2417): Cd-WARNING **: failed to get session [pid 10586]: No such device or address

Does this also fit into this bug or is it another bug?

Aug 13 11:17:44 localhost gnome-session[18660]: (gnome-settings-daemon:18691): color-plugin-WARNING **: failed to connect to device: Failed to connect to missing device /org/freedesktop/ColorManager/devices/cups_HP_LaserJet_1020
Aug 13 11:17:44 localhost gnome-session[18660]: (gnome-settings-daemon:18691): color-plugin-WARNING **: failed to connect to device: Failed to connect to missing device /org/freedesktop/ColorManager/devices/cups_PDF