Den Fehler gibt es im Launchpad unter Bug #1613027 genau beschrieben aber noch keine Lösung!
Ich helfe mir erst mal mit einem 2. PC der noch 14.04 drauf hat. Da funktioniert der Scannerzugriff!
Aber vielleicht hat jemand ja eine Idee zu folgender Fehlermeldung von simple-scan mit Ubuntu 16.04:
bino@bino-lan:~$ simple-scan -d
[+0,01s] DEBUG: simple-scan.vala:674: Starting Simple Scan 3.20.0, PID=25489
[+0,01s] DEBUG: Connecting to session manager
[+0,07s] DEBUG: ui.vala:2032: Loading state from /home/bino/.cache/simple-scan/state
[+0,07s] DEBUG: ui.vala:1995: Restoring window to 600x400 pixels
[+0,07s] DEBUG: autosave-manager.vala:64: Loading autosave information
[+0,07s] DEBUG: autosave-manager.vala:259: Waiting to autosave...
[+0,07s] CRITICAL: gtk_event_controller_reset: assertion 'GTK_IS_EVENT_CONTROLLER (controller)' failed
[+0,13s] DEBUG: scanner.vala:1447: sane_init () -> SANE_STATUS_GOOD
[+0,13s] DEBUG: scanner.vala:1453: SANE version 1.0.25
[+0,13s] DEBUG: scanner.vala:1514: Requesting redetection of scan devices
[+0,13s] DEBUG: scanner.vala:803: Processing request
[+0,18s] DEBUG: autosave-manager.vala:281: Autosaving book information
[+0,26s] DEBUG: ui.vala:2124: Saving state to /home/bino/.cache/simple-scan/state
[+5,39s] DEBUG: ui.vala:2124: Saving state to /home/bino/.cache/simple-scan/state
[+5,58s] DEBUG: ui.vala:2124: Saving state to /home/bino/.cache/simple-scan/state
[+5,81s] DEBUG: scanner.vala:338: sane_get_devices () -> SANE_STATUS_GOOD
[+5,81s] DEBUG: scanner.vala:350: Device: name="pixma:MX870_MX870.fritz.box" vendor="CANON" model="Canon PIXMA MX870" type="multi-function peripheral"
[+12,90s] DEBUG: simple-scan.vala:404: Requesting scan at 300 dpi from device 'pixma:MX870_MX870.fritz.box'
[+12,90s] DEBUG: scanner.vala:1560: Scanner.scan ("pixma:MX870_MX870.fritz.box", dpi=300, scan_mode=ScanMode.COLOR, depth=8, type=ScanType.SINGLE, paper_width=2100, paper_height=2970, brightness=0, contrast=0)
[+12,90s] DEBUG: scanner.vala:803: Processing request
[+13,01s] DEBUG: ui.vala:2124: Saving state to /home/bino/.cache/simple-scan/state
[+13,45s] DEBUG: scanner.vala:864: sane_open ("pixma:MX870_MX870.fritz.box") -> SANE_STATUS_INVAL
[+13,45s] WARNING: scanner.vala:868: Unable to get open device: Invalid argument
[+13,80s] DEBUG: ui.vala:2124: Saving state to /home/bino/.cache/simple-scan/state
[+15,43s] DEBUG: ui.vala:2124: Saving state to /home/bino/.cache/simple-scan/state
[+18,66s] DEBUG: ui.vala:2124: Saving state to /home/bino/.cache/simple-scan/state
[+19,29s] DEBUG: ui.vala:2124: Saving state to /home/bino/.cache/simple-scan/state
[+19,43s] DEBUG: ui.vala:2124: Saving state to /home/bino/.cache/simple-scan/state
[+20,35s] DEBUG: ui.vala:2124: Saving state to /home/bino/.cache/simple-scan/state
[+21,99s] DEBUG: autosave-manager.vala:195: Deleting autosave records
[+21,99s] DEBUG: scanner.vala:1587: Stopping scan thread
[+21,99s] DEBUG: scanner.vala:803: Processing request
[+22,00s] DEBUG: scanner.vala:1598: sane_exit ()
bino@bino-lan:~$
Zum Vergleich dazu mit Ubuntu 14.04 füge ich folgenden Anhang hinzu: