Error message : "Failed to scan - unable to connect to scanner" when using simple-scan

[Barbara Schulz]

1) System and program information:
I am using Ubuntu 20.04 LTS and am trying to use the brother printer/scanner combo MFC-J5910DW in order to scan documents with simple-scan:

simple-scan:
 Installed: 3.36.0-0ubuntu1
  Candidate: 3.36.0-0ubuntu1
  Version table:
 *** 3.36.0-0ubuntu1 500
        500 http://de.archive.ubuntu.com/ubuntu focal/main amd64 Packages
        100 /var/lib/dpkg/status

2) Description of what I did and what happened:
I downloaded and installed the newest scanner driver deb-packages (2 of them) from the official brother web-page and installed them using

$ sudo apt-get install ./'sannerdirverfilename'.deb

and there was no error message. So I also installed simple-scan from the Ubuntu repository using:

$ sudo apt-get install simple-scan

This also worked just fine. But when I now try to use simple-scan, it doesn't work. I call the program from the terminal command line:

$ simple scan

and it opens an interactive window, searches for a scanner and finds the brother scanner. But when I then hit the 'scan' button, I get the error message

"Failed to scan - unable to connect to scanner"

3) Error Log for simple-scan:
So I used simple-scan with the debug option, and here is the log-file:

$ simple-scan --debug
[+0,00s] DEBUG: simple-scan.vala:638: Starting simple-scan 3.36.0, PID=7992
[+0,00s] DEBUG: unsetenv() is not thread-safe and should not be used after threads are created
[+0,02s] DEBUG: _g_io_module_get_default: Found default implementation dconf (DConfSettingsBackend) for ‘gsettings-backend’
[+0,06s] DEBUG: app-window.vala:1908: Loading state from /home/barbara/.cache/simple-scan/state
[+0,06s] DEBUG: app-window.vala:1887: Restoring window to 600x400 pixels
[+0,33s] DEBUG: app-window.vala:1983: Saving state to /home/barbara/.cache/simple-scan/state
[+6,00s] DEBUG: scanner.vala:1541: sane_init () -> SANE_STATUS_GOOD
[+6,00s] DEBUG: scanner.vala:1547: SANE version 1.0.29
[+6,00s] DEBUG: scanner.vala:1608: Requesting redetection of scan devices
[+6,00s] DEBUG: scanner.vala:828: Processing request
[+6,15s] DEBUG: app-window.vala:1983: Saving state to /home/barbara/.cache/simple-scan/state
[+14,91s] DEBUG: scanner.vala:341: sane_get_devices () -> SANE_STATUS_GOOD
[+14,91s] DEBUG: scanner.vala:353: Device: name="brother4:bus2;dev2" vendor="Brother" model="MFC-J5910DW" type="USB scanner"
[+15,02s] DEBUG: app-window.vala:1983: Saving state to /home/barbara/.cache/simple-scan/state
[+41,02s] DEBUG: simple-scan.vala:455: Requesting scan at 150 dpi from device 'brother4:bus2;dev2'
[+41,02s] DEBUG: scanner.vala:1676: Scanner.scan ("brother4:bus2;dev2", dpi=150, scan_mode=ScanMode.GRAY, depth=2, type=single, paper_width=0, paper_height=0, brightness=0, contrast=0, delay=3000ms)
[+41,02s] DEBUG: scanner.vala:828: Processing request
[+41,02s] DEBUG: scanner.vala:889: sane_open ("brother4:bus2;dev2") -> SANE_STATUS_IO_ERROR
[+41,02s] WARNING: scanner.vala:893: Unable to open device: Error during device I/O
[+41,43s] DEBUG: app-window.vala:1983: Saving state to /home/barbara/.cache/simple-scan/state
[+56,27s] DEBUG: app-window.vala:1983: Saving state to /home/barbara/.cache/simple-scan/state
[+100,09s] DEBUG: autosave-manager.vala:201: Deleting autosave records
[+100,09s] DEBUG: scanner.vala:1704: Stopping scan thread
[+100,09s] DEBUG: scanner.vala:828: Processing request
[+100,09s] DEBUG: scanner.vala:1715: sane_exit ()

I have no idea why sane cannot open the I/O device.

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: simple-scan 3.36.0-0ubuntu1
ProcVersionSignature: Ubuntu 5.4.0-29.33-generic 5.4.30
Uname: Linux 5.4.0-29-generic x86_64
ApportVersion: 2.20.11-0ubuntu27
Architecture: amd64
CasperMD5CheckResult: skip
CurrentDesktop: ubuntu:GNOME
Date: Sat May 16 07:54:46 2020
InstallationDate: Installed on 2020-04-24 (21 days ago)
InstallationMedia: Ubuntu 20.04 LTS "Focal Fossa" - Release amd64 (20200423)
MachineType: Dell Inc. Latitude E5450
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-5.4.0-29-generic root=UUID=2bb62112-1254-42cd-ba84-e3f2edc0d4b2 ro quiet splash vt.handoff=7
SimpleScanLog:

SourcePackage: simple-scan
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 07/30/2015
dmi.bios.vendor: Dell Inc.
dmi.bios.version: A08
dmi.board.name: 0DCPV1
dmi.board.vendor: Dell Inc.
dmi.board.version: A00
dmi.chassis.type: 9
dmi.chassis.vendor: Dell Inc.
dmi.modalias: dmi:bvnDellInc.:bvrA08:bd07/30/2015:svnDellInc.:pnLatitudeE5450:pvr:rvnDellInc.:rn0DCPV1:rvrA00:cvnDellInc.:ct9:cvr:
dmi.product.name: Latitude E5450
dmi.product.sku: 062B
dmi.sys.vendor: Dell Inc.

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Igor Shabalov (ishabalov)]

Have exactly same error with Brother MFS-L8900CDW
Upgraded from 18.04.5 - was working well before upgrade.

[corrado venturini (corradoventu)]

I have same error with HP Deskjet 2630 and simple-scan 3.38.1-1 on Ubuntu 21.04
was ok before some upgrades.