Pro:~$ simple-scan -d
[+0.00s] DEBUG: simple-scan.vala:674: Starting Simple Scan 3.20.0, PID=7779
[+0.00s] DEBUG: Connecting to session manager
[+0.03s] DEBUG: ui.vala:2032: Loading state from /home/tom/.cache/simple-scan/state
[+0.03s] DEBUG: ui.vala:1995: Restoring window to 600x400 pixels
[+0.03s] DEBUG: autosave-manager.vala:64: Loading autosave information
[+0.03s] DEBUG: autosave-manager.vala:259: Waiting to autosave...
[+0.03s] CRITICAL: gtk_event_controller_reset: assertion 'GTK_IS_EVENT_CONTROLLER (controller)' failed
[+0.07s] DEBUG: scanner.vala:1447: sane_init () -> SANE_STATUS_GOOD
[+0.07s] DEBUG: scanner.vala:1453: SANE version 1.0.25
[+0.07s] DEBUG: scanner.vala:1514: Requesting redetection of scan devices
[+0.07s] DEBUG: scanner.vala:803: Processing request
[+0.13s] DEBUG: autosave-manager.vala:281: Autosaving book information
[+0.18s] DEBUG: ui.vala:2124: Saving state to /home/tom/.cache/simple-scan/state
[+4.98s] DEBUG: simple-scan.vala:404: Requesting scan at 150 dpi from device '(null)'
[+4.98s] DEBUG: scanner.vala:1560: Scanner.scan ("(null)", dpi=150, scan_mode=ScanMode.GRAY, depth=2, type=ScanType.SINGLE, paper_width=0, paper_height=0, brightness=0, contrast=0)
[+4.98s] DEBUG: ui.vala:2124: Saving state to /home/tom/.cache/simple-scan/state
[+5.09s] DEBUG: ui.vala:2124: Saving state to /home/tom/.cache/simple-scan/state
[+5.67s] DEBUG: scanner.vala:338: sane_get_devices () -> SANE_STATUS_GOOD
[+5.67s] DEBUG: scanner.vala:350: Device: name="pixma:MP620_Cannon" vendor="CANON" model="Canon PIXMA MP620" type="multi-function peripheral"
[+5.67s] DEBUG: scanner.vala:803: Processing request
[+5.89s] DEBUG: ui.vala:2124: Saving state to /home/tom/.cache/simple-scan/state
[+6.66s] DEBUG: scanner.vala:864: sane_open ("pixma:MP620_Cannon") -> SANE_STATUS_INVAL
[+6.66s] WARNING: scanner.vala:868: Unable to get open device: Invalid argument
[+7.01s] DEBUG: ui.vala:2124: Saving state to /home/tom/.cache/simple-scan/state
[+16.62s] DEBUG: ui.vala:2124: Saving state to /home/tom/.cache/simple-scan/state