Same problem if I use hp:/usb/deskjet_995c?serial=MY1581C042AP URI (detected automatically when I pluged USB cable). Logs from dmesg (adding printer) : [ 9016.640000] usb 3-1: new full speed USB device using uhci_hcd and address 5 [ 9016.856000] usb 3-1: configuration #1 chosen from 1 choice [ 9017.452000] /build/buildd/linux-source-2.6.22-2.6.22/drivers/usb/class/usblp.c: usblp0: USB Bidirectional printer dev 5 if 0 alt 0 proto 2 vid 0x03F0 pid 0x5004 [ 9017.452000] usbcore: registered new interface driver usblp [ 9017.452000] /build/buildd/linux-source-2.6.22-2.6.22/drivers/usb/class/usblp.c: v0.13: USB Printer Device Class driver Logs from /var/log/syslog : Oct 1 21:43:42 Id2ndR-U200 kernel: [ 9017.452000] /build/buildd/linux-source-2.6.22-2.6.22/drivers/usb/class/usblp.c: v0.13: USB Printer Device Class driver Oct 1 21:43:42 Id2ndR-U200 NetworkManager: [1191267822.604751] nm_hal_device_added(): New device added (hal udi is '/org/freedesktop/Hal/devices/usb_device_3f0_5004_MY1581C042AP_usbraw'). Oct 1 21:43:42 Id2ndR-U200 hal_lpadmin: add Oct 1 21:43:44 Id2ndR-U200 hal_lpadmin: URIs: ['hp:/usb/deskjet_995c?serial=MY1581C042AP', 'usb://HP/DESKJET%20995C?serial=MY1581C042AP', 'hal:///org/freedesktop/Hal/devices/usb_device_3f0_5004_MY1581C042AP_if0_printer_MY1581C042AP'] Oct 1 21:43:45 Id2ndR-U200 python: hp-probe[21214]: warning: No devices found on the 'usb' bus. If this isn't the result you are expecting, Oct 1 21:43:45 Id2ndR-U200 python: hp-probe[21214]: warning: check to make sure your devices are properly connected and powered on. Oct 1 21:43:45 Id2ndR-U200 hal_lpadmin: HPLIP Fax URIs: None Oct 1 21:43:45 Id2ndR-U200 hal_lpadmin: Calling GetReady Oct 1 21:43:56 Id2ndR-U200 hal_lpadmin: Device ID: MFG:HEWLETT-PACKARD;MDL:DESKJET 995C;DES:hewlett-packard deskjet 995c;CMD:MLC,PCL,PML,DW-PCL; URI:hp:/usb/deskjet_995c?serial=MY1581C042AP Oct 1 21:43:56 Id2ndR-U200 hal_lpadmin: PPD: foomatic:HP-DeskJet_995C-hpijs.ppd; Status: 0 Oct 1 21:44:06 Id2ndR-U200 hal_lpadmin: Added printer DESKJET_995C Oct 1 21:44:07 Id2ndR-U200 python: hp-probe[21249]: warning: No devices found on the 'usb' bus. If this isn't the result you are expecting, Oct 1 21:44:07 Id2ndR-U200 python: hp-probe[21249]: warning: check to make sure your devices are properly connected and powered on. Oct 1 21:44:07 Id2ndR-U200 NetworkManager: [1191267847.940116] nm_hal_device_added(): New device added (hal udi is '/org/freedesktop/Hal/devices/usb_device_3f0_5004_MY1581C042AP_if0_printer_MY1581C042AP'). New job send. Logs from /var/log/syslog : Oct 1 21:44:55 Id2ndR-U200 deskjet_995c?serial=MY1581C042AP: io/hpmud/musb.c 549: invalid product id string: Operation not permitted Oct 1 21:44:55 Id2ndR-U200 deskjet_995c?serial=MY1581C042AP: io/hpmud/musb.c 1003: unable to open hp:/usb/deskjet_995c?serial=MY1581C042AP Oct 1 21:44:55 Id2ndR-U200 deskjet_995c?serial=MY1581C042AP: INFO: open device failed; will retry in 30 seconds... Oct 1 21:44:55 Id2ndR-U200 kernel: [ 9090.244000] audit(1191267894.873:28): type=1503 operation="inode_permission" requested_mask="rw" denied_mask="rw" name="/dev/tty" pid=21269 profile="/usr/sbin/cupsd" Oct 1 21:44:55 Id2ndR-U200 kernel: [ 9090.284000] audit(1191267894.873:29): type=1503 operation="inode_permission" requested_mask="rw" denied_mask="rw" name="/dev/tty" pid=21272 profile="/usr/sbin/cupsd" Oct 1 21:44:55 Id2ndR-U200 hpijs: io/hpmud/musb.c 549: invalid product id string: Operation not permitted Oct 1 21:44:55 Id2ndR-U200 hpijs: io/hpmud/musb.c 1003: unable to open hp:/usb/deskjet_995c?serial=MY1581C042AP Oct 1 21:45:25 Id2ndR-U200 deskjet_995c?serial=MY1581C042AP: io/hpmud/musb.c 549: invalid product id string: Operation not permitted Oct 1 21:45:25 Id2ndR-U200 deskjet_995c?serial=MY1581C042AP: io/hpmud/musb.c 1003: unable to open hp:/usb/deskjet_995c?serial=MY1581C042AP Oct 1 21:45:25 Id2ndR-U200 deskjet_995c?serial=MY1581C042AP: INFO: open device failed; will retry in 30 seconds... Oct 1 21:45:42 Id2ndR-U200 hp: io/hpmud/musb.c 1880: invalid product id string: Operation not permitted Oct 1 21:45:42 Id2ndR-U200 hp: io/hpmud/musb.c 1885: invalid serial id string: Operation not permitted Oct 1 21:45:43 Id2ndR-U200 python: io/hpmud/musb.c 1880: invalid product id string: Operation not permitted Oct 1 21:45:43 Id2ndR-U200 python: io/hpmud/musb.c 1885: invalid serial id string: Operation not permitted Oct 1 21:45:52 Id2ndR-U200 hp: io/hpmud/musb.c 1880: invalid product id string: Operation not permitted Oct 1 21:45:52 Id2ndR-U200 hp: io/hpmud/musb.c 1885: invalid serial id string: Operation not permitted Oct 1 21:45:52 Id2ndR-U200 python: io/hpmud/musb.c 1880: invalid product id string: Operation not permitted Oct 1 21:45:52 Id2ndR-U200 python: io/hpmud/musb.c 1885: invalid serial id string: Operation not permitted ... After changing URI to usb://HP/DESKJET%20995C?serial=MY1581C042AP, it works.