My SPM and SM both are showing libsane and sane-util as not being installed, plus there are no broken dependencies. However, the archives are still showing them on the list, so I suspect if I try to reinstall I'll create the same problem. Now what do I do?

Archive list section

/var/cache/apt/archives/libsane_1.0.23-3ubuntu3.1_amd64.deb
/var/cache/apt/archives/libsane-common_1.0.23-3ubuntu3.1_amd64.deb (this is installed)
/var/cache/apt/archives/lock
/var/cache/apt/archives/sane-utils_1.0.23-3ubuntu3.1_amd64.deb

Now you could do an "apt-get purge libsane sane-utils" if you want to get rid of any configuration files they left around.

After that, assuming you actually want those packages for something (using a scanner or other dependencies), do an "apt-get update" and go ahead and install them "apt-get install libsane sane-utils". It should work this time if the stale configuration files were removed.

The "apt-get update" will always replace your stale packages in the cache. As mentioned, you can get rid of them with "apt-get clean" but it shouldn't change anything.

crabbyfogey, did you solve it? with crazy-yiuf's advice?

from what i see you were always getting the same error, pointing to one file, and always aiming and shooting elsewhere.
hope you didn't thoroughly bork your system by now.

the Package libsane can be removed via edit in /var/lib/dpkg/status
But that is an advanced topic that I will not cover here nor provide direction.

That's the how and what of it.
What SMP and PM shows, IDK, I don't rely on GUIs much.

Good Luck.

may offer additional relief.
Ask your Doctor.

Couple of questions:
Error: E: /var/cache/apt/archives/libsane_1.0.23-3ubuntu3.1_amd64.deb: trying to overwrite shared '/etc/sane.d/v4l.conf', which is different from other instances of package libsane:amd64
Doesn't this say that the error occurs while trying to overwrite v4l.conf? If that file is deleted will a different one be installed?

Contents of v4l.conf:
#
# In order to use the v4linux backend you have to give the device
# You can enable multiple lines if
# you really have multible v4l devices.

# Backends disabled, to re-enable unquote the following lines
# See https://bugs.launchpad.net/ubuntu/+s...nds/+bug/87312
#/dev/bttv0
#/dev/video0
#/dev/video1
#/dev/video2
#/dev/video3

What does that even do? Bug#87312 is from 2007, is about tv cards recognised as scanners and looks like it has been fixed.

That's exactly right, and that's what we want to happen. What's supposed to happen in this case is a nice prompt, something like "This package wants to replace a configuration file, is that ok?", but package maintainers make mistakes, and sometimes an upgrade path falls through the cracks.

Every line in that file is commented out - it does literally nothing. Its purpose is to allow you to uncomment the lines by removing the # at the beginning of the line. Then that line would be parsed by the program when it starts up.

You should remove /etc/sane.d/v4l.conf and let the new version replace it. You can either do it manually with the rm command or via the package manager with the command "sudo apt-get purge libsane".

Different file name this time:
(synaptic:5081): GLib-CRITICAL **: g_child_watch_add_full: assertion 'pid > 0' failed
(Reading database ... 177424 files and directories currently installed.)
Preparing to unpack .../libsane_1.0.23-3ubuntu3.1_amd64.deb ...
Unpacking libsane:amd64 (1.0.23-3ubuntu3.1) ...
dpkg: error processing archive /var/cache/apt/archives/libsane_1.0.23-3ubuntu3.1_amd64.deb (--unpack):
trying to overwrite shared '/etc/sane.d/snapscan.conf', which is different from other instances of package libsane:amd64
Errors were encountered while processing:
/var/cache/apt/archives/libsane_1.0.23-3ubuntu3.1_amd64.deb
E: Sub-process /usr/bin/dpkg returned an error code (1)
A package failed to install. Trying to recover:
dpkg: dependency problems prevent configuration of sane-utils:
sane-utils depends on libsane; however:
Package libsane:amd64 is not installed.

dpkg: error processing package sane-utils (--configure):
dependency problems - leaving unconfigured
Errors were encountered while processing:
sane-utils

File Contents:
--------------------------
#------------------------------ General -----------------------------------

# Change to the fully qualified filename of your firmware file, if
# firmware upload is needed by the scanner
firmware /usr/share/sane/snapscan/your-firmwarefile.bin

# If not automatically found you may manually specify a device name.

# For USB scanners also specify bus=usb, e.g.
# /dev/usb/scanner0 bus=usb

# For SCSI scanners specify the generic device, e.g. /dev/sg0 on Linux.
# /dev/sg0

#---------------------------------------------------------------------------
# No changes should be necessary below this line
#---------------------------------------------------------------------------

#-------------------------- SCSI scanners ----------------------------------
# These SCSI devices will be probed automatically
scsi AGFA * Scanner
scsi COLOR * Scanner
scsi Color * Scanner
scsi ACERPERI * Scanner

#--------------------------- USB scanners -----------------------------------
# These USB devices will be probed automatically
# (This will currently work only on Linux)

# Benq/Acer/Vuego 310U
usb 0x04a5 0x1a20
usb 0x04a5 0x1a26

# Benq/Acer/Vuego 320U
usb 0x04a5 0x2022

# Benq/Acer/Vuego 620U / 620UT
usb 0x04a5 0x1a2a
usb 0x04a5 0x2040

# Benq/Acer/Vuego 640U
usb 0x04a5 0x2060

# Benq/Acer/Vuego 640BU
usb 0x04a5 0x207e

# Benq/Acer/Vuego 640BT
usb 0x04a5 0x20be

# Benq/Acer/Vuego 1240U
usb 0x04a5 0x20c0

# Benq/Acer/Vuego 3300 / 4300
usb 0x04a5 0x20b0

# Benq/Acer/Vuego 4300
usb 0x04a5 0x20de

# Benq 5000E / 5000U
usb 0x04a5 0x20f8

# Benq 5000
usb 0x04a5 0x20fc

# Benq/Acer 5300
usb 0x04a5 0x20fe

# Benq 5250C
usb 0x04a5 0x2137

# Agfa 1236U
usb 0x06bd 0x0002

# Agfa 1212U
usb 0x06bd 0x0001
usb 0x06bd 0x2061

# Agfa Snapscan e10
usb 0x06bd 0x2093

# Agfa Snapscan e20
usb 0x06bd 0x2091

# Agfa Snapscan e25
usb 0x06bd 0x2095

# Agfa Snapscan e26
usb 0x06bd 0x2097

# Agfa Snapscan e40
usb 0x06bd 0x208d

# Agfa Snapscan e42
usb 0x06bd 0x20ff

# Agfa Snapscan e50
usb 0x06bd 0x208f

# Agfa Snapscan e52
usb 0x06bd 0x20fd

# Epson Perfection 660
usb 0x04b8 0x0114

# Epson Perfection 1670
usb 0x04b8 0x011f

# Epson Perfection 2480
usb 0x04b8 0x0121

# Epson Perfection 3490
usb 0x04b8 0x0122

# Epson Stylus CX-1500
usb 0x04b8 0x080c

The scanner I want to use is not on the list, should I just remove this one, too? If I remove all the rest of the error files will sane-util reinstall new ones?

It should. Anything you didn't add manually will presumably be added when it reconfigures.

I recommend
If you haven't already, to remove all of the stale configuration files at once.

If your scanner doesn't work afterwards, you can run the command recommended by Habitual:
And if it still doesn't work you can start a new thread.

Eureka! Sane-util installed no broken anything! Now all I have to do is figure out how to test the scanner. That's a whole nuther smoke. Thanks so much for the digital hand holding.

Good job and well done.
Feels good doesn't it?

Wouldn't be the first busted deb package that apt installed.
Ubuntu 16.04-based apache2 install used to "bark", then half-install, it was a mess.
Until...
and a serious edit described in post #19.

Like I said, I don't trust GUIs much.
But occasionally, they can be useful.

Feeling kind of proud of myself. Getting the scanner to work will probably end that. I'm not as nervous using the terminal, but still think I need a magic decoder ring. Anyway, it's all good.

plug in scanner.
Turn it on.
Run xsane.

Easy peasy, mac-n-cheesy

I think where I'm going to run into trouble is that it's a copier/printer/scanner combo. Fired it up and the copier/printer work fine, haven't tackled the scanner yet. Everything I've read online is outdated and complicated, so I'm doing some homework first. Finding it hard to believe all that online stuff is necessary. The sane docs say I should install sane-back-end first (pixma 0.17.23)- can't find it to look at it??

"outdated" based on "publication date"?

copier/printer might be the best you get since it's
this pixma 0.17.23

SANE - Installing a scanner that isn't auto-detected

and look at "pixma 0.17.23" over on http://www.sane-project.org/sane-mfgs.html#SCANNERS

We'll likely need more info and I advise starting a new thread for that.
Don't do anything but look and read/bookmark

Checked the sane support list before I bought it, so it's on there. The only thing I've done so far is do a sane-find-scanner. Looks like it can see it but can't get there from here.

# sane-find-scanner will now attempt to detect your scanner. If the
# result is different from what you expected, first make sure your
# scanner is powered up and properly connected to your computer.

# No SCSI scanners found. If you expected something different, make sure that
# you have loaded a kernel SCSI driver for your SCSI adapter.

found USB scanner (vendor=0x0bda [Generic], product=0x0129 [USB2.0-CRW]) at libusb:001:003
could not fetch string descriptor: Pipe error
could not fetch string descriptor: Pipe error
could not fetch string descriptor: Pipe error
could not fetch string descriptor: Pipe error
# Your USB scanner was (probably) detected. It may or may not be supported by
# SANE. Try scanimage -L and read the backend's manpage.

# Not checking for parallel port scanners.

# Most Scanners connected to the parallel port or other proprietary ports
# can't be detected by this program.

While rummaging thru other forums, someone said that you shouldn't install xsane before the back-end??? Anyway, as you say, that's another thread. As soon as I figure out what questions to ask.